Vulnerabilities (CVE)

Zulip is an open-source team collaboration tool. From 5.0 to before 11.5, some administrative actions on the user profile were susceptible to stored XSS in group names or channel names. Exploiting these vulnerabilities required the user explicitly interacting with the problematic object. This vulnerability is fixed in 11.5.

Zulip is an open-source team collaboration tool. Zulip supports a configuration where account creation is limited solely by being able to authenticate with a single-sign on authentication backend, meaning the organization places no restrictions on email address domains or invitations being required to join, but has disabled the EmailAuthBackend that is used for email/password authentication. A bug in the Zulip server means that it is possible to create an account in such organizations, without h ... Zulip is an open-source team collaboration tool. Zulip supports a configuration where account creation is limited solely by being able to authenticate with a single-sign on authentication backend, meaning the organization places no restrictions on email address domains or invitations being required to join, but has disabled the EmailAuthBackend that is used for email/password authentication. A bug in the Zulip server means that it is possible to create an account in such organizations, without having an account with the configured SSO authentication backend. This issue is patched in version 10.2. A workaround includes requiring invitations to join the organization prevents the vulnerability from being accessed.

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Zulip is an open-source team chat application. From versions 2.0.0-rc1 to before 10.4 in Zulip Server, the /digest/ URL of a server shows a preview of what the email weekly digest would contain. This URL, though not the digest itself, contains a cross-site scripting (XSS) vulnerability in both topic names and channel names. This issue has been fixed in Zulip Server 10.4. A workaround for this issue involves denying access to /digest/.

Zulip server provides an open-source team chat that helps teams stay productive and focused. Zulip Server 7.0 and above are vulnerable to an information disclose attack, where, if a Zulip server is hosting multiple organizations, an unauthenticated user can make a request and determine if an email address is in use by a user. Zulip Server 9.4 resolves the issue, as does the `main` branch of Zulip Server. Users are advised to upgrade. There are no known workarounds for this issue.

Zulip server provides an open-source team chat that helps teams stay productive and focused. Prior to 10.0, the data export to organization administrators feature in Zulip leaks private data. The collection of user-agent types identifying specific integrations or HTTP libraries (E.g., ZulipGitlabWebhook, okhttp, or PycURL) that have been used to access any organization on the server was incorrectly included in all three export types, regardless of if they were used to access the exported organiz ... Zulip server provides an open-source team chat that helps teams stay productive and focused. Prior to 10.0, the data export to organization administrators feature in Zulip leaks private data. The collection of user-agent types identifying specific integrations or HTTP libraries (E.g., ZulipGitlabWebhook, okhttp, or PycURL) that have been used to access any organization on the server was incorrectly included in all three export types, regardless of if they were used to access the exported organization or not. The "public data" and "with consent" exports metadata including the titles of some topics in private channels which the administrator otherwise did not have access to, and none of the users consented to exporting and metadata for which users were in a group DM together. This vulnerability is fixed in 10.0.

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Zulip is an open-source team collaboration tool. The API for deleting an organization custom profile field is supposed to be restricted to organization administrators, but its handler failed to check that the field belongs to the same organization as the user. Therefore, an administrator of any organization was incorrectly allowed to delete custom profile fields belonging to a different organization. This is fixed in Zulip Server 10.1.

Zulip is an open-source team collaboration tool. When a user moves a Zulip message, they have the option to move all messages in the topic, move only subsequent messages as well, or move just a single message. If the user chose to just move one message, and was moving it from a public stream to a private stream, Zulip would successfully move the message, -- but active users who did not have access to the private stream, but whose client had already received the message, would continue to see th ... Zulip is an open-source team collaboration tool. When a user moves a Zulip message, they have the option to move all messages in the topic, move only subsequent messages as well, or move just a single message. If the user chose to just move one message, and was moving it from a public stream to a private stream, Zulip would successfully move the message, -- but active users who did not have access to the private stream, but whose client had already received the message, would continue to see the message in the public stream until they reloaded their client. Additionally, Zulip did not remove view permissions on the message from recently-active users, allowing the message to show up in the "All messages" view or in search results, but not in "Inbox" or "Recent conversations" views. While the bug has been present since moving messages between streams was first introduced in version 3.0, this option became much more common starting in Zulip 8.0, when the default option in the picker for moving the very last message in a conversation was changed. This issue is fixed in Zulip Server 8.3. No known workarounds are available.

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In Zulip Server before 1.7.1, on a server with multiple realms, a vulnerability in the invitation system lets an authorized user of one realm on the server create a user account on any other realm.

An error in the implementation of an autosubscribe feature in the check_stream_exists route of the Zulip group chat application server before 1.4.3 allowed an authenticated user to subscribe to a private stream that should have required an invitation from an existing member to join. The issue affects all previously released versions of the Zulip server.

Zulip Server 1.5.1 and below suffer from an error in the implementation of the invite_by_admins_only setting in the Zulip group chat application server that allowed an authenticated user to invite other users to join a Zulip organization even if the organization was configured to prevent this.

Zulip from 8.0 to 8.3 contains a memory leak vulnerability in the handling of popovers.

Zulip is an open-source team collaboration tool. A vulnerability in version 8.0 is similar to CVE-2023-32677, but applies to multi-use invitations, not single-use invitation links as in the prior CVE. Specifically, it applies when the installation has configured non-admins to be able to invite users and create multi-use invitations, and has also configured only admins to be able to invite users to streams. As in CVE-2023-32677, this does not let users invite new users to arbitrary streams, only ... Zulip is an open-source team collaboration tool. A vulnerability in version 8.0 is similar to CVE-2023-32677, but applies to multi-use invitations, not single-use invitation links as in the prior CVE. Specifically, it applies when the installation has configured non-admins to be able to invite users and create multi-use invitations, and has also configured only admins to be able to invite users to streams. As in CVE-2023-32677, this does not let users invite new users to arbitrary streams, only to streams that the inviter can already see. Version 8.1 fixes this issue. As a workaround, administrators can limit sending of invitations down to users who also have the permission to add users to streams.

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Zulip is an open-source team collaboration tool. It was discovered by the Zulip development team that active users who had previously been subscribed to a stream incorrectly continued being able to use the Zulip API to access metadata for that stream. As a result, users who had been removed from a stream, but still had an account in the organization, could still view metadata for that stream (including the stream name, description, settings, and an email address used to send emails into the stre ... Zulip is an open-source team collaboration tool. It was discovered by the Zulip development team that active users who had previously been subscribed to a stream incorrectly continued being able to use the Zulip API to access metadata for that stream. As a result, users who had been removed from a stream, but still had an account in the organization, could still view metadata for that stream (including the stream name, description, settings, and an email address used to send emails into the stream via the incoming email integration). This potentially allowed users to see changes to a stream’s metadata after they had lost access to the stream. This vulnerability has been addressed in version 7.5 and all users are advised to upgrade. There are no known workarounds for this issue.

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Zulip is an open-source team collaboration tool with unique topic-based threading that combines the best of email and chat to make remote work productive and delightful. The main development branch of Zulip Server from May 2, 2023 and later, including beta versions 7.0-beta1 and 7.0-beta2, is vulnerable to a cross-site scripting vulnerability in tooltips on the message feed. An attacker who can send messages could maliciously craft a topic for the message, such that a victim who hovers the toolt ... Zulip is an open-source team collaboration tool with unique topic-based threading that combines the best of email and chat to make remote work productive and delightful. The main development branch of Zulip Server from May 2, 2023 and later, including beta versions 7.0-beta1 and 7.0-beta2, is vulnerable to a cross-site scripting vulnerability in tooltips on the message feed. An attacker who can send messages could maliciously craft a topic for the message, such that a victim who hovers the tooltip for that topic in their message feed triggers execution of JavaScript code controlled by the attacker.

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Zulip is an open-source team collaboration tool with topic-based threading that combines email and chat. Users who used to be subscribed to a private stream and have been removed from it since retain the ability to edit messages/topics, move messages to other streams, and delete messages that they used to have access to, if other relevant organization permissions allow these actions. For example, a user may be able to edit or delete their old messages they posted in such a private stream. An adm ... Zulip is an open-source team collaboration tool with topic-based threading that combines email and chat. Users who used to be subscribed to a private stream and have been removed from it since retain the ability to edit messages/topics, move messages to other streams, and delete messages that they used to have access to, if other relevant organization permissions allow these actions. For example, a user may be able to edit or delete their old messages they posted in such a private stream. An administrator will be able to delete old messages (that they had access to) from the private stream. This issue was fixed in Zulip Server version 7.3.

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Zulip is an open-source team collaboration tool. In versions of zulip prior to commit `2f6c5a8` but after commit `04cf68b` users could upload files with arbitrary `Content-Type` which would be served from the Zulip hostname with `Content-Disposition: inline` and no `Content-Security-Policy` header, allowing them to trick other users into executing arbitrary Javascript in the context of the Zulip application. Among other things, this enables session theft. Only deployments which use the S3 stora ... Zulip is an open-source team collaboration tool. In versions of zulip prior to commit `2f6c5a8` but after commit `04cf68b` users could upload files with arbitrary `Content-Type` which would be served from the Zulip hostname with `Content-Disposition: inline` and no `Content-Security-Policy` header, allowing them to trick other users into executing arbitrary Javascript in the context of the Zulip application. Among other things, this enables session theft. Only deployments which use the S3 storage (not the local-disk storage) are affected, and only deployments which deployed commit 04cf68b45ebb5c03247a0d6453e35ffc175d55da, which has only been in `main`, not any numbered release. Users affected should upgrade from main again to deploy this fix. Switching from S3 storage to the local-disk storage would nominally mitigate this, but is likely more involved than upgrading to the latest `main` which addresses the issue.

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Zulip is an open-source team collaboration tool. For organizations with System for Cross-domain Identity Management(SCIM) account management enabled, Zulip Server 5.0 through 5.6 checked the SCIM bearer token using a comparator that did not run in constant time. Therefore, it might theoretically be possible for an attacker to infer the value of the token by performing a sophisticated timing analysis on a large number of failing requests. If successful, this would allow the attacker to impersonat ... Zulip is an open-source team collaboration tool. For organizations with System for Cross-domain Identity Management(SCIM) account management enabled, Zulip Server 5.0 through 5.6 checked the SCIM bearer token using a comparator that did not run in constant time. Therefore, it might theoretically be possible for an attacker to infer the value of the token by performing a sophisticated timing analysis on a large number of failing requests. If successful, this would allow the attacker to impersonate the SCIM client for its abilities to read and update user accounts in the Zulip organization. Organizations where SCIM account management has not been enabled are not affected.

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Zulip is an open-source team collaboration tool. Zulip Server versions 2.1.0 above have a user interface tool, accessible only to server owners and server administrators, which provides a way to download a "public data" export. While this export is only accessible to administrators, in many configurations server administrators are not expected to have access to private messages and private streams. However, the "public data" export which administrators could generate contained the attachment con ... Zulip is an open-source team collaboration tool. Zulip Server versions 2.1.0 above have a user interface tool, accessible only to server owners and server administrators, which provides a way to download a "public data" export. While this export is only accessible to administrators, in many configurations server administrators are not expected to have access to private messages and private streams. However, the "public data" export which administrators could generate contained the attachment contents for all attachments, even those from private messages and streams. Zulip Server version 5.4 contains a patch for this issue.

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Zulip is an open source team chat app. The `main` development branch of Zulip Server from June 2021 and later is vulnerable to a cross-site scripting vulnerability on the recent topics page. An attacker could maliciously craft a full name for their account and send messages to a topic with several participants; a victim who then opens an overflow tooltip including this full name on the recent topics page could trigger execution of JavaScript code controlled by the attacker. Users running a Zulip ... Zulip is an open source team chat app. The `main` development branch of Zulip Server from June 2021 and later is vulnerable to a cross-site scripting vulnerability on the recent topics page. An attacker could maliciously craft a full name for their account and send messages to a topic with several participants; a victim who then opens an overflow tooltip including this full name on the recent topics page could trigger execution of JavaScript code controlled by the attacker. Users running a Zulip server from the main branch should upgrade from main (2022-03-01 or later) again to deploy this fix.

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Zulip is an open-source team collaboration tool with topic-based threading. Zulip Server version 2.0.0 and above are vulnerable to insufficient access control with multi-use invitations. A Zulip Server deployment which hosts multiple organizations is vulnerable to an attack where an invitation created in one organization (potentially as a role with elevated permissions) can be used to join any other organization. This bypasses any restrictions on required domains on users' email addresses, may b ... Zulip is an open-source team collaboration tool with topic-based threading. Zulip Server version 2.0.0 and above are vulnerable to insufficient access control with multi-use invitations. A Zulip Server deployment which hosts multiple organizations is vulnerable to an attack where an invitation created in one organization (potentially as a role with elevated permissions) can be used to join any other organization. This bypasses any restrictions on required domains on users' email addresses, may be used to gain access to organizations which are only accessible by invitation, and may be used to gain access with elevated privileges. This issue has been patched in release 4.10. There are no known workarounds for this issue. ### Patches _Has the problem been patched? What versions should users upgrade to?_ ### Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_ ### References _Are there any links users can visit to find out more?_ ### For more information If you have any questions or comments about this advisory, you can discuss them on the [developer community Zulip server](https://zulip.com/developer-community/), or email the [Zulip security team](mailto:[email protected]).

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In the topic moving API in Zulip Server 3.x before 3.4, organization administrators were able to move messages to streams in other organizations hosted by the same Zulip installation.

An issue was discovered in Zulip Server before 3.4. A bug in the implementation of the all_public_streams API feature resulted in guest users being able to receive message traffic to public streams that should have been only accessible to members of the organization.

An issue was discovered in Zulip Server before 3.4. A bug in the implementation of the can_forge_sender permission (previously is_api_super_user) resulted in users with this permission being able to send messages appearing as if sent by a system bot, including to other organizations hosted by the same Zulip installation.

An issue was discovered in Zulip Server before 3.4. A bug in the implementation of replies to messages sent by outgoing webhooks to private streams meant that an outgoing webhook bot could be used to send messages to private streams that the user was not intended to be able to send messages to.

Zulip Server before 2.1.3 allows XSS via the modal_link feature in the Markdown functionality.

Zulip Server before 2.1.3 allows reverse tabnabbing via the Markdown functionality.

Zulip Server 2.x before 2.1.7 allows eval injection if a privileged attacker were able to write directly to the postgres database, and chose to write a crafted custom profile field value.

Zulip Server before 2.1.5 has Incorrect Access Control because 0198_preregistrationuser_invited_as adds the administrator role to invitations.

Zulip Server before 2.1.5 allows reverse tabnapping via a topic header link.

Zulip Server before 2.1.5 allows reflected XSS via the Dropbox webhook.

Zulip Server before 2.1.3 allows XSS via a Markdown link, with resultant account takeover.

The image thumbnailing handler in Zulip Server versions 1.9.0 to before 2.0.8 allowed an open redirect that was visible to logged-in users.

In Zulip Server versions from 1.7.0 to before 2.0.7, a bug in the new user signup process meant that users who registered their account using social authentication (e.g., GitHub or Google SSO) in an organization that also allows password authentication could have their personal API key stolen by an unprivileged attacker, allowing nearly full access to the user's account.

Zulip server before 2.0.5 incompletely validated the MIME types of uploaded files. A user who is logged into the server could upload files of certain types to mount a stored cross-site scripting attack on other logged-in users. On a Zulip server using the default local uploads backend, the attack is only effective against browsers lacking support for Content-Security-Policy such as Internet Explorer 11. On a Zulip server using the S3 uploads backend, the attack is confined to the origin of the c ... Zulip server before 2.0.5 incompletely validated the MIME types of uploaded files. A user who is logged into the server could upload files of certain types to mount a stored cross-site scripting attack on other logged-in users. On a Zulip server using the default local uploads backend, the attack is only effective against browsers lacking support for Content-Security-Policy such as Internet Explorer 11. On a Zulip server using the S3 uploads backend, the attack is confined to the origin of the configured S3 uploads hostname and cannot reach the Zulip server itself.

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The Markdown parser in Zulip server before 2.0.5 used a regular expression vulnerable to exponential backtracking. A user who is logged into the server could send a crafted message causing the server to spend an effectively arbitrary amount of CPU time and stall the processing of future messages.

In Zulip Server versions before 1.7.2, there was an XSS issue with user uploads and the (default) LOCAL_UPLOADS_DIR storage backend.

In Zulip Server versions before 1.7.2, there was an XSS issue with stream names in topic typeahead.

In Zulip Server versions 1.5.x, 1.6.x, and 1.7.x before 1.7.2, there was an XSS issue with muting notifications.

In Zulip Server versions before 1.7.2, there were XSS issues with the frontend markdown processor.