A vulnerability was found in libxml2. Processing certain sch:name elements from the input XML file can trigger a memory corruption issue. This flaw allows an attacker to craft a malicious XML input file that can lead libxml to crash, resulting in a denial of service or other possible undefined behavior due to sensitive data being corrupted in memory.

A Heap Use After Free (UAF) vulnerability was discovered in the Schematron in the libxml2. The issue arises in the xmlSchematronGetNode function when processing XPath expressions in Schematron schema elements <sch:name path="..."/>, where a pointer to freed memory is returned and then accessed, leading to undefined behavior and potential crashes.

A critical stack overflow vulnerability was discovered in the libxslt library when handling the dyn:map() function from the EXSLT extension. The vulnerability allows an attacker to cause a denial of service (DoS) via a specially crafted XSLT document containing the recursive dyn:map(., .) call.

The main reason of the vulnerability is that the exsltDynMapFunction function in libexslt/dynamic.c doesn’t contain a recursion depth check. When handling dyn:map(., .) where the second parameter contains a recursive call to the same function, infinite recursion occurs until the program stack is exhausted.

Integer Overflow (Wraparound) vulnerability in the xmlBuildQName() function in libxml2. The flaw arises due to unsafe arithmetic when concatenating XML name components using the lengths of prefix and local name. These lengths, originally sizet, are cast to int, leading to incorrect calculations when values are large. If exploited, the function can perform a memcpy with an extremely large size, causing a stack buffer overflow. This vulnerability is remotely exploitable if the attacker can influence XML content passed to affected applications, potentially resulting in denial of service.

Stack-based buffer overflow vulnerability in the interactive shell of the xmllint tool in libxml2. The issue is caused by an unsafe use of strcpy() when processing user-supplied command-line input. When an attacker passes an overly long argument to any shell command (e.g., exit, cat, etc.), the input exceeds the fixed-size stack buffer, resulting in a crash or potentially arbitrary code execution on systems lacking stack protections. This vulnerability affects only the interactive shell and requires that an attacker can influence or control the command input to xmllint, which is uncommon in typical deployments.

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, 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.

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.

Accessibility. A logging issue was addressed with improved data redaction.

Last updated 25 February 2025

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.

A flaw was found in libxml2. This vulnerability occurs when the library processes a specially crafted XML Schema Definition (XSD) validated document that includes an internal entity reference. An attacker could exploit this by providing a malicious document, leading to a type confusion error that causes the application to crash. This results in a denial of service (DoS), making the affected system or application unavailable.

Use After Free in libxml2's xmlParseInternalSubset from GNOME libxml2 version 2.9.11 to 2.11.0 allows a remote attacker to cause a denial-of-service via maliciously crafted XML input with improper entity resolution handling.

A vulnerability was found in libxml2 up to 2.14.5. It has been declared as problematic. This vulnerability affects the function xmlParseSGMLCatalog of the component xmlcatalog. The manipulation leads to uncontrolled recursion. Attacking locally is a requirement. The exploit has been disclosed to the public and may be used. The real existence of this vulnerability is still doubted at the moment. The code maintainer explains, that "[t]he issue can only be triggered with untrusted SGML catalogs and it makes absolutely no sense to use untrusted catalogs. I also doubt that anyone is still using SGML catalogs at all."

Severity: Medium

Affected versions:

- upstream versions - 2.9.11 to 2.11.0

Description:

Credit:

Geoffrey Humphreys (reporter)

References: https://bugs.launchpad.net/ubuntu/+source/libxml2/+bug/2141260 https://gitlab.gnome.org/GNOME/libxml2/-/workitems/1058

The linked launchpad issue has PoC and reproduction instructions if needed.

Timeline: 2026-02-09 : reported to Canonical's Ubuntu Security Team 2026-02-17 : reported to upstream 2026-06-08 : PoC and details send to distros list 2026-06-22 : public disclosure

Accessibility. A logging issue was addressed with improved data redaction.

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

Reference and upstream commit: https://gitlab.gnome.org/GNOME/libxml2/commit/0e1a49c89076

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

Reference and upstream commit: https://gitlab.gnome.org/GNOME/libxml2/mergerequests/68

A vulnerability in libxml2 when parsing specially crafted XML document if XZ support is enabled causing DoS of application was found.

CVE request (including reproducer):

http://seclists.org/oss-sec/2015/q4/206

A null pointer dereference vulnerability was discovered in the libxml2. The issue occurs in the xmlSchematronFormatReport function when processing incorrect XPath expressions in Schematron schema reports, leading to undefined behavior and potential crashes.