Vulnerabilities (CVE)

During a renegotiation handshake if the Encrypt-Then-Mac extension is negotiated where it was not in the original handshake (or vice-versa) then this can cause OpenSSL 1.1.0 before 1.1.0e to crash (dependent on ciphersuite). Both clients and servers are affected.

OpenSSL 1.0.2 (starting from version 1.0.2b) introduced an "error state" mechanism. The intent was that if a fatal error occurred during a handshake then OpenSSL would move into the error state and would immediately fail if you attempted to continue the handshake. This works as designed for the explicit handshake functions (SSL_do_handshake(), SSL_accept() and SSL_connect()), however due to a bug it does not work correctly if SSL_read() or SSL_write() is called directly. In that scenario, if the ... OpenSSL 1.0.2 (starting from version 1.0.2b) introduced an "error state" mechanism. The intent was that if a fatal error occurred during a handshake then OpenSSL would move into the error state and would immediately fail if you attempted to continue the handshake. This works as designed for the explicit handshake functions (SSL_do_handshake(), SSL_accept() and SSL_connect()), however due to a bug it does not work correctly if SSL_read() or SSL_write() is called directly. In that scenario, if the handshake fails then a fatal error will be returned in the initial function call. If SSL_read()/SSL_write() is subsequently called by the application for the same SSL object then it will succeed and the data is passed without being decrypted/encrypted directly from the SSL/TLS record layer. In order to exploit this issue an application bug would have to be present that resulted in a call to SSL_read()/SSL_write() being issued after having already received a fatal error. OpenSSL version 1.0.2b-1.0.2m are affected. Fixed in OpenSSL 1.0.2n. OpenSSL 1.1.0 is not affected.

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A denial of service flaw was found in OpenSSL 0.9.8, 1.0.1, 1.0.2 through 1.0.2h, and 1.1.0 in the way the TLS/SSL protocol defined processing of ALERT packets during a connection handshake. A remote attacker could use this flaw to make a TLS/SSL server consume an excessive amount of CPU and fail to accept connections from other clients.

There is a carry propagating bug in the Broadwell-specific Montgomery multiplication procedure in OpenSSL 1.0.2 and 1.1.0 before 1.1.0c that handles input lengths divisible by, but longer than 256 bits. Analysis suggests that attacks against RSA, DSA and DH private keys are impossible. This is because the subroutine in question is not used in operations with the private key itself and an input of the attacker's direct choice. Otherwise the bug can manifest itself as transient authentication and ... There is a carry propagating bug in the Broadwell-specific Montgomery multiplication procedure in OpenSSL 1.0.2 and 1.1.0 before 1.1.0c that handles input lengths divisible by, but longer than 256 bits. Analysis suggests that attacks against RSA, DSA and DH private keys are impossible. This is because the subroutine in question is not used in operations with the private key itself and an input of the attacker's direct choice. Otherwise the bug can manifest itself as transient authentication and key negotiation failures or reproducible erroneous outcome of public-key operations with specially crafted input. Among EC algorithms only Brainpool P-512 curves are affected and one presumably can attack ECDH key negotiation. Impact was not analyzed in detail, because pre-requisites for attack are considered unlikely. Namely multiple clients have to choose the curve in question and the server has to share the private key among them, neither of which is default behaviour. Even then only clients that chose the curve will be affected.

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There is a carry propagating bug in the x86_64 Montgomery squaring procedure in OpenSSL before 1.0.2m and 1.1.0 before 1.1.0g. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH are considered just feasible (although very difficult) because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources ... There is a carry propagating bug in the x86_64 Montgomery squaring procedure in OpenSSL before 1.0.2m and 1.1.0 before 1.1.0g. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH are considered just feasible (although very difficult) because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be very significant and likely only accessible to a limited number of attackers. An attacker would additionally need online access to an unpatched system using the target private key in a scenario with persistent DH parameters and a private key that is shared between multiple clients. This only affects processors that support the BMI1, BMI2 and ADX extensions like Intel Broadwell (5th generation) and later or AMD Ryzen.

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There is a carry propagating bug in the x86_64 Montgomery squaring procedure in OpenSSL 1.0.2 before 1.0.2k and 1.1.0 before 1.1.0d. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH are considered just feasible (although very difficult) because most of the work necessary to deduce information about a private key may be performed offline. The amount of res ... There is a carry propagating bug in the x86_64 Montgomery squaring procedure in OpenSSL 1.0.2 before 1.0.2k and 1.1.0 before 1.1.0d. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH are considered just feasible (although very difficult) because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be very significant and likely only accessible to a limited number of attackers. An attacker would additionally need online access to an unpatched system using the target private key in a scenario with persistent DH parameters and a private key that is shared between multiple clients. For example this can occur by default in OpenSSL DHE based SSL/TLS ciphersuites. Note: This issue is very similar to CVE-2015-3193 but must be treated as a separate problem.

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If an SSL/TLS server or client is running on a 32-bit host, and a specific cipher is being used, then a truncated packet can cause that server or client to perform an out-of-bounds read, usually resulting in a crash. For OpenSSL 1.1.0, the crash can be triggered when using CHACHA20/POLY1305; users should upgrade to 1.1.0d. For Openssl 1.0.2, the crash can be triggered when using RC4-MD5; users who have not disabled that algorithm should update to 1.0.2k.

In OpenSSL 1.1.0 before 1.1.0c, applications parsing invalid CMS structures can crash with a NULL pointer dereference. This is caused by a bug in the handling of the ASN.1 CHOICE type in OpenSSL 1.1.0 which can result in a NULL value being passed to the structure callback if an attempt is made to free certain invalid encodings. Only CHOICE structures using a callback which do not handle NULL value are affected.

While parsing an IPAddressFamily extension in an X.509 certificate, it is possible to do a one-byte overread. This would result in an incorrect text display of the certificate. This bug has been present since 2006 and is present in all versions of OpenSSL before 1.0.2m and 1.1.0g.

In OpenSSL 1.1.0 before 1.1.0c, TLS connections using *-CHACHA20-POLY1305 ciphersuites are susceptible to a DoS attack by corrupting larger payloads. This can result in an OpenSSL crash. This issue is not considered to be exploitable beyond a DoS.

ssl/s2_srvr.c in OpenSSL 1.0.1 before 1.0.1r and 1.0.2 before 1.0.2f does not prevent use of disabled ciphers, which makes it easier for man-in-the-middle attackers to defeat cryptographic protection mechanisms by performing computations on SSLv2 traffic, related to the get_client_master_key and get_client_hello functions.

Integer underflow in the EVP_DecodeUpdate function in crypto/evp/encode.c in the base64-decoding implementation in OpenSSL before 0.9.8za, 1.0.0 before 1.0.0m, and 1.0.1 before 1.0.1h allows remote attackers to cause a denial of service (memory corruption) or possibly have unspecified other impact via crafted base64 data that triggers a buffer overflow.

The ASN.1 signature-verification implementation in the rsa_item_verify function in crypto/rsa/rsa_ameth.c in OpenSSL 1.0.2 before 1.0.2a allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via crafted RSA PSS parameters to an endpoint that uses the certificate-verification feature.

d1_both.c in the DTLS implementation in OpenSSL 0.9.8 before 0.9.8zb, 1.0.0 before 1.0.0n, and 1.0.1 before 1.0.1i allows remote attackers to cause a denial of service (memory consumption) via crafted DTLS handshake messages that trigger memory allocations corresponding to large length values.

The ASN.1 implementation in OpenSSL before 1.0.1o and 1.0.2 before 1.0.2c allows remote attackers to execute arbitrary code or cause a denial of service (buffer underflow and memory corruption) via an ANY field in crafted serialized data, aka the "negative zero" issue.

Memory leak in the SRP_VBASE_get_by_user implementation in OpenSSL 1.0.1 before 1.0.1s and 1.0.2 before 1.0.2g allows remote attackers to cause a denial of service (memory consumption) by providing an invalid username in a connection attempt, related to apps/s_server.c and crypto/srp/srp_vfy.c.

Memory leak in d1_srtp.c in the DTLS SRTP extension in OpenSSL 1.0.1 before 1.0.1j allows remote attackers to cause a denial of service (memory consumption) via a crafted handshake message.

Multiple memory leaks in t1_lib.c in OpenSSL before 1.0.1u, 1.0.2 before 1.0.2i, and 1.1.0 before 1.1.0a allow remote attackers to cause a denial of service (memory consumption) via large OCSP Status Request extensions.

The ASN1_TYPE_cmp function in crypto/asn1/a_type.c in OpenSSL before 0.9.8zf, 1.0.0 before 1.0.0r, 1.0.1 before 1.0.1m, and 1.0.2 before 1.0.2a does not properly perform boolean-type comparisons, which allows remote attackers to cause a denial of service (invalid read operation and application crash) via a crafted X.509 certificate to an endpoint that uses the certificate-verification feature.

Multiple integer overflows in OpenSSL 1.0.1 before 1.0.1s and 1.0.2 before 1.0.2g allow remote attackers to cause a denial of service (heap memory corruption or NULL pointer dereference) or possibly have unspecified other impact via a long digit string that is mishandled by the (1) BN_dec2bn or (2) BN_hex2bn function, related to crypto/bn/bn.h and crypto/bn/bn_print.c.

Race condition in the ssl_parse_serverhello_tlsext function in t1_lib.c in OpenSSL 1.0.0 before 1.0.0n and 1.0.1 before 1.0.1i, when multithreading and session resumption are used, allows remote SSL servers to cause a denial of service (memory overwrite and client application crash) or possibly have unspecified other impact by sending Elliptic Curve (EC) Supported Point Formats Extension data.

The ssl_set_client_disabled function in t1_lib.c in OpenSSL 1.0.1 before 1.0.1i allows remote SSL servers to cause a denial of service (NULL pointer dereference and client application crash) via a ServerHello message that includes an SRP ciphersuite without the required negotiation of that ciphersuite with the client.

The ssl3_read_bytes function in record/rec_layer_s3.c in OpenSSL 1.1.0 before 1.1.0a allows remote attackers to cause a denial of service (infinite loop) by triggering a zero-length record in an SSL_peek call.

The asn1_d2i_read_bio function in crypto/asn1/a_d2i_fp.c in the ASN.1 BIO implementation in OpenSSL before 1.0.1t and 1.0.2 before 1.0.2h allows remote attackers to cause a denial of service (memory consumption) via a short invalid encoding.

ssl/s3_clnt.c in OpenSSL 1.0.0 before 1.0.0t, 1.0.1 before 1.0.1p, and 1.0.2 before 1.0.2d, when used for a multi-threaded client, writes the PSK identity hint to an incorrect data structure, which allows remote servers to cause a denial of service (race condition and double free) via a crafted ServerKeyExchange message.

The ssl3_send_client_key_exchange function in s3_clnt.c in OpenSSL 0.9.8 before 0.9.8zb, 1.0.0 before 1.0.0n, and 1.0.1 before 1.0.1i allows remote DTLS servers to cause a denial of service (NULL pointer dereference and client application crash) via a crafted handshake message in conjunction with a (1) anonymous DH or (2) anonymous ECDH ciphersuite.

The fmtstr function in crypto/bio/b_print.c in OpenSSL 1.0.1 before 1.0.1s and 1.0.2 before 1.0.2g improperly calculates string lengths, which allows remote attackers to cause a denial of service (overflow and out-of-bounds read) or possibly have unspecified other impact via a long string, as demonstrated by a large amount of ASN.1 data, a different vulnerability than CVE-2016-2842.

The ssl3_get_key_exchange function in s3_clnt.c in OpenSSL before 0.9.8zd, 1.0.0 before 1.0.0p, and 1.0.1 before 1.0.1k allows remote SSL servers to conduct ECDHE-to-ECDH downgrade attacks and trigger a loss of forward secrecy by omitting the ServerKeyExchange message.

The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabled on a server but not on a client, does not properly convey a DHE_EXPORT choice, which allows man-in-the-middle attackers to conduct cipher-downgrade attacks by rewriting a ClientHello with DHE replaced by DHE_EXPORT and then rewriting a ServerHello with DHE_EXPORT replaced by DHE, aka the "Logjam" issue.

The state-machine implementation in OpenSSL 1.1.0 before 1.1.0a allocates memory before checking for an excessive length, which might allow remote attackers to cause a denial of service (memory consumption) via crafted TLS messages, related to statem/statem.c and statem/statem_lib.c.

The ssl23_get_client_hello function in s23_srvr.c in OpenSSL 1.0.1 before 1.0.1i allows man-in-the-middle attackers to force the use of TLS 1.0 by triggering ClientHello message fragmentation in communication between a client and server that both support later TLS versions, related to a "protocol downgrade" issue.

The ssl3_client_hello function in s3_clnt.c in OpenSSL 1.0.2 before 1.0.2a does not ensure that the PRNG is seeded before proceeding with a handshake, which makes it easier for remote attackers to defeat cryptographic protection mechanisms by sniffing the network and then conducting a brute-force attack.

The do_ssl3_write function in s3_pkt.c in OpenSSL 1.x through 1.0.1g, when SSL_MODE_RELEASE_BUFFERS is enabled, does not properly manage a buffer pointer during certain recursive calls, which allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via vectors that trigger an alert condition.

Integer overflow in the MDC2_Update function in crypto/mdc2/mdc2dgst.c in OpenSSL before 1.1.0 allows remote attackers to cause a denial of service (out-of-bounds write and application crash) or possibly have unspecified other impact via unknown vectors.

The ssl3_get_cert_verify function in s3_srvr.c in OpenSSL 1.0.0 before 1.0.0p and 1.0.1 before 1.0.1k accepts client authentication with a Diffie-Hellman (DH) certificate without requiring a CertificateVerify message, which allows remote attackers to obtain access without knowledge of a private key via crafted TLS Handshake Protocol traffic to a server that recognizes a Certification Authority with DH support.

OpenSSL before 0.9.8zd, 1.0.0 before 1.0.0p, and 1.0.1 before 1.0.1k does not enforce certain constraints on certificate data, which allows remote attackers to defeat a fingerprint-based certificate-blacklist protection mechanism by including crafted data within a certificate's unsigned portion, related to crypto/asn1/a_verify.c, crypto/dsa/dsa_asn1.c, crypto/ecdsa/ecs_vrf.c, and crypto/x509/x_all.c.

The X509_cmp_time function in crypto/x509/x509_vfy.c in OpenSSL before 0.9.8zg, 1.0.0 before 1.0.0s, 1.0.1 before 1.0.1n, and 1.0.2 before 1.0.2b allows remote attackers to cause a denial of service (out-of-bounds read and application crash) via a crafted length field in ASN1_TIME data, as demonstrated by an attack against a server that supports client authentication with a custom verification callback.

Memory leak in the tls_decrypt_ticket function in t1_lib.c in OpenSSL before 0.9.8zc, 1.0.0 before 1.0.0o, and 1.0.1 before 1.0.1j allows remote attackers to cause a denial of service (memory consumption) via a crafted session ticket that triggers an integrity-check failure.

The SSLv2 protocol, as used in OpenSSL before 1.0.1s and 1.0.2 before 1.0.2g and other products, requires a server to send a ServerVerify message before establishing that a client possesses certain plaintext RSA data, which makes it easier for remote attackers to decrypt TLS ciphertext data by leveraging a Bleichenbacher RSA padding oracle, aka a "DROWN" attack.

Race condition in the ssl3_get_new_session_ticket function in ssl/s3_clnt.c in OpenSSL before 0.9.8zg, 1.0.0 before 1.0.0s, 1.0.1 before 1.0.1n, and 1.0.2 before 1.0.2b, when used for a multi-threaded client, allows remote attackers to cause a denial of service (double free and application crash) or possibly have unspecified other impact by providing a NewSessionTicket during an attempt to reuse a ticket that had been obtained earlier.