Vulnerabilities (CVE)

A flaw was found in libxml2's xmlBuildQName function, where integer overflows in buffer size calculations can lead to a stack-based buffer overflow. This issue can result in memory corruption or a denial of service when processing crafted input.

parser.c in libxml2 before 2.9.5 does not prevent infinite recursion in parameter entities.

libxml2 20904-GITv2.9.4-16-g0741801 is vulnerable to a heap-based buffer over-read in the xmlDictComputeFastKey function in dict.c. This vulnerability causes programs that use libxml2, such as PHP, to crash. This vulnerability exists because of an incomplete fix for libxml2 Bug 759398.

libxml2 20904-GITv2.9.4-16-g0741801 is vulnerable to a stack-based buffer overflow. The function xmlSnprintfElementContent in valid.c is supposed to recursively dump the element content definition into a char buffer 'buf' of size 'size'. At the end of the routine, the function may strcat two more characters without checking whether the current strlen(buf) + 2 < size. This vulnerability causes programs that use libxml2, such as PHP, to crash.

libxml2 20904-GITv2.9.4-16-g0741801 is vulnerable to a heap-based buffer over-read in the xmlDictAddString function in dict.c. This vulnerability causes programs that use libxml2, such as PHP, to crash. This vulnerability exists because of an incomplete fix for CVE-2016-1839.

xmlSchemaPreRun in xmlschemas.c in libxml2 2.9.10 allows an xmlSchemaValidateStream memory leak.

The htmlParseTryOrFinish function in HTMLparser.c in libxml2 2.9.4 allows attackers to cause a denial of service (buffer over-read) or information disclosure.

The xmlNextChar function in libxml2 before 2.9.4 allows remote attackers to cause a denial of service (heap-based buffer over-read) via a crafted XML document.

Heap-based buffer overflow in the xmlStrncat function in libxml2 before 2.9.4, as used in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted XML document.

libxml2 2.9.4 and earlier, as used in XMLSec 1.2.23 and earlier and other products, does not offer a flag directly indicating that the current document may be read but other files may not be opened, which makes it easier for remote attackers to conduct XML External Entity (XXE) attacks via a crafted document.

Use-after-free vulnerability in libxml2 through 2.9.4, as used in Google Chrome before 52.0.2743.82, allows remote attackers to cause a denial of service or possibly have unspecified other impact via vectors related to the XPointer range-to function.

The xmlStringGetNodeList function in tree.c in libxml2 2.9.3 and earlier, when used in recovery mode, allows context-dependent attackers to cause a denial of service (infinite recursion, stack consumption, and application crash) via a crafted XML document.

A flaw in libxml2 allows remote XML entity inclusion with default parser flags (i.e., when the caller did not request entity substitution, DTD validation, external DTD subset loading, or default DTD attributes). Depending on the context, this may expose a higher-risk attack surface in libxml2 not usually reachable with default parser flags, and expose content from local files, HTTP, or FTP servers (which might be otherwise unreachable).

An integer overflow in xmlmemory.c in libxml2 before 2.9.5, as used in Google Chrome prior to 62.0.3202.62 and other products, allowed a remote attacker to potentially exploit heap corruption via a crafted XML file.

A NULL pointer dereference vulnerability exists in the xpath.c:xmlXPathCompOpEval() function of libxml2 through 2.9.8 when parsing an invalid XPath expression in the XPATH_OP_AND or XPATH_OP_OR case. Applications processing untrusted XSL format inputs with the use of the libxml2 library may be vulnerable to a denial of service attack due to a crash of the application.

xmlParseBalancedChunkMemoryRecover in parser.c in libxml2 before 2.9.10 has a memory leak related to newDoc->oldNs.

xmlStringLenDecodeEntities in parser.c in libxml2 2.9.10 has an infinite loop in a certain end-of-file situation.

There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this flaw is to application availability, with some potential impact to confidentiality and integrity if an attacker is able to use memory information to further exploit the application.

In libxml2 2.11 before 2.11.9, 2.12 before 2.12.9, and 2.13 before 2.13.3, the SAX parser can produce events for external entities even if custom SAX handlers try to override entity content (by setting "checked"). This makes classic XXE attacks possible.

An issue was discovered in xmllint (from libxml2) before 2.11.8 and 2.12.x before 2.12.7. Formatting error messages with xmllint --htmlout can result in a buffer over-read in xmlHTMLPrintFileContext in xmllint.c.

NULL Pointer Dereference allows attackers to cause a denial of service (or application crash). This only applies when lxml is used together with libxml2 2.9.10 through 2.9.14. libxml2 2.9.9 and earlier are not affected. It allows triggering crashes through forged input data, given a vulnerable code sequence in the application. The vulnerability is caused by the iterwalk function (also used by the canonicalize function). Such code shouldn't be in wide-spread use, given that parsing + iterwalk wou ... NULL Pointer Dereference allows attackers to cause a denial of service (or application crash). This only applies when lxml is used together with libxml2 2.9.10 through 2.9.14. libxml2 2.9.9 and earlier are not affected. It allows triggering crashes through forged input data, given a vulnerable code sequence in the application. The vulnerability is caused by the iterwalk function (also used by the canonicalize function). Such code shouldn't be in wide-spread use, given that parsing + iterwalk would usually be replaced with the more efficient iterparse function. However, an XML converter that serialises to C14N would also be vulnerable, for example, and there are legitimate use cases for this code sequence. If untrusted input is received (also remotely) and processed via iterwalk function, a crash can be triggered.

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Possible cross-site scripting vulnerability in libxml after commit 960f0e2.

libxml2 before 2.12.10 and 2.13.x before 2.13.6 has a NULL pointer dereference in xmlPatMatch in pattern.c.

libxml2 before 2.12.10 and 2.13.x before 2.13.6 has a stack-based buffer overflow in xmlSnprintfElements in valid.c. To exploit this, DTD validation must occur for an untrusted document or untrusted DTD. NOTE: this is similar to CVE-2017-9047.

An issue was discovered in libxml2 before 2.11.7 and 2.12.x before 2.12.5. When using the XML Reader interface with DTD validation and XInclude expansion enabled, processing crafted XML documents can lead to an xmlValidatePopElement use-after-free.

libxml2 before 2.12.10 and 2.13.x before 2.13.6 has a use-after-free in xmlSchemaIDCFillNodeTables and xmlSchemaBubbleIDCNodeTables in xmlschemas.c. To exploit this, a crafted XML document must be validated against an XML schema with certain identity constraints, or a crafted XML schema must be used.

libxml2 through 2.11.5 has a use-after-free that can only occur after a certain memory allocation fails. This occurs in xmlUnlinkNode in tree.c. NOTE: the vendor's position is "I don't think these issues are critical enough to warrant a CVE ID ... because an attacker typically can't control when memory allocations fail."

Xmlsoft Libxml2 v2.11.0 was discovered to contain an out-of-bounds read via the xmlSAX2StartElement() function at /libxml2/SAX2.c. This vulnerability allows attackers to cause a Denial of Service (DoS) via supplying a crafted XML file. NOTE: the vendor's position is that the product does not support the legacy SAX1 interface with custom callbacks; there is a crash even without crafted input.

xmlXIncludeAddNode in xinclude.c in libxml2 before 2.11.0 has a use-after-free.

A flaw was found in the interactive shell of the xmllint command-line tool, used for parsing XML files. When a user inputs an overly long command, the program does not check the input size properly, which can cause it to crash. This issue might allow attackers to run harmful code in rare configurations without modern protections.

In libxml2 before 2.13.8 and 2.14.x before 2.14.2, xmlSchemaIDCFillNodeTables in xmlschemas.c has a heap-based buffer under-read. To exploit this, a crafted XML document must be validated against an XML schema with certain identity constraints, or a crafted XML schema must be used.

In libxml2 before 2.13.8 and 2.14.x before 2.14.2, out-of-bounds memory access can occur in the Python API (Python bindings) because of an incorrect return value. This occurs in xmlPythonFileRead and xmlPythonFileReadRaw because of a difference between bytes and characters.

Uncontrolled recursion in XPath evaluation in libxml2 up to and including version 2.9.14 allows a local attacker to cause a stack overflow via crafted expressions. XPath processing functions `xmlXPathRunEval`, `xmlXPathCtxtCompile`, and `xmlXPathEvalExpr` were resetting recursion depth to zero before making potentially recursive calls. When such functions were called recursively this could allow for uncontrolled recursion and lead to a stack overflow. These functions now preserve recursion depth ... Uncontrolled recursion in XPath evaluation in libxml2 up to and including version 2.9.14 allows a local attacker to cause a stack overflow via crafted expressions. XPath processing functions `xmlXPathRunEval`, `xmlXPathCtxtCompile`, and `xmlXPathEvalExpr` were resetting recursion depth to zero before making potentially recursive calls. When such functions were called recursively this could allow for uncontrolled recursion and lead to a stack overflow. These functions now preserve recursion depth across recursive calls, allowing recursion depth to be controlled.

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In libxml2 before 2.10.4, parsing of certain invalid XSD schemas can lead to a NULL pointer dereference and subsequently a segfault. This occurs in xmlSchemaFixupComplexType in xmlschemas.c.

valid.c in libxml2 before 2.9.13 has a use-after-free of ID and IDREF attributes.

An issue was discovered in libxml2 before 2.10.3. When parsing a multi-gigabyte XML document with the XML_PARSE_HUGE parser option enabled, several integer counters can overflow. This results in an attempt to access an array at a negative 2GB offset, typically leading to a segmentation fault.

An issue was discovered in libxml2 before 2.10.3. Certain invalid XML entity definitions can corrupt a hash table key, potentially leading to subsequent logic errors. In one case, a double-free can be provoked.

A buffer overflow was discovered in libxml2 20904-GITv2.9.4-16-g0741801. The function xmlSnprintfElementContent in valid.c is supposed to recursively dump the element content definition into a char buffer 'buf' of size 'size'. The variable len is assigned strlen(buf). If the content->type is XML_ELEMENT_CONTENT_ELEMENT, then (i) the content->prefix is appended to buf (if it actually fits) whereupon (ii) content->name is written to the buffer. However, the check for whether the content->name actu ... A buffer overflow was discovered in libxml2 20904-GITv2.9.4-16-g0741801. The function xmlSnprintfElementContent in valid.c is supposed to recursively dump the element content definition into a char buffer 'buf' of size 'size'. The variable len is assigned strlen(buf). If the content->type is XML_ELEMENT_CONTENT_ELEMENT, then (i) the content->prefix is appended to buf (if it actually fits) whereupon (ii) content->name is written to the buffer. However, the check for whether the content->name actually fits also uses 'len' rather than the updated buffer length strlen(buf). This allows us to write about "size" many bytes beyond the allocated memory. This vulnerability causes programs that use libxml2, such as PHP, to crash.

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parser.c in libxml2 before 2.9.5 mishandles parameter-entity references because the NEXTL macro calls the xmlParserHandlePEReference function in the case of a '%' character in a DTD name.

The xmlBufAttrSerializeTxtContent function in xmlsave.c in libxml2 allows context-dependent attackers to cause a denial of service (out-of-bounds read and application crash) via a non-UTF-8 attribute value, related to serialization. NOTE: this vulnerability may be a duplicate of CVE-2016-3627.