Vulnerabilities

libxml2 before 2.15.4 fails to propagate parser flags in the xmlXIncludeProcess and xmlXIncludeProcessTree functions, so options such as XML_PARSE_NONET are not applied during XInclude processing. An application that relies on that flag to block network access, while using a custom resource loader that can reach the internet, can be tricked into fetching attacker-controlled external entities or remote resources. This enables XML external entity (XXE) injection, server-side request forgery (SSRF), and denial of service via deliberately slow attacker-controlled internet resources, with high impact to confidentiality, integrity, and availability (CVSS 3.1: 7.8). Any product that embeds a vulnerable libxml2 and calls the affected XInclude functions is affected, with the xmlsoft project as the maintaining vendor. No public proof-of-concept or confirmed in-the-wild exploitation is known, EPSS is low (0.2% in 30 days), and the issue is not listed in the CISA KEV catalog.

Do: Upgrade libxml2 to 2.15.4 or later, or apply your Linux distribution's backported security patch. Developers whose code calls xmlXIncludeProcess or xmlXIncludeProcessTree should audit whether they rely on XML_PARSE_NONET for network isolation, and mitigate by restricting or hardening custom resource loaders, disabling XInclude on untrusted XML input, and enforcing egress filtering. Remember that bundled or vendored copies of libxml2 inside language bindings and third-party software may need separate updates from the OS package.

libxml2 is vulnerable to multiple stack-based buffer overflows in the xmlcatalog utility when running in --shell mode. The usershell() function processes user input using fixed-size stack buffers without proper bounds checking. By supplying an overly long input line, an attacker can overflow internal buffers (command, arg, and argv) during input parsing. This results in memory corruption within the stack frame. Successful exploitation may cause a crash or potentially allow arbitrary code execution in the context of the xmlcatalog process. This issue has been fixed in the commit c2e233fc. NOTE: The maintainers of this project did not agree that this issue is a vulnerability and considered it a bug.

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 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.

A flaw was found in libxml2, an XML parsing library. This uncontrolled recursion vulnerability occurs in the xmlCatalogXMLResolveURI function when an XML catalog contains a delegate URI entry that references itself. A remote attacker could exploit this configuration-dependent issue by providing a specially crafted XML catalog, leading to infinite recursion and call stack exhaustion. This ultimately results in a segmentation fault, causing a Denial of Service (DoS) by crashing affected applications.

A flaw was identified in the RelaxNG parser of libxml2 related to how external schema inclusions are handled. The parser does not enforce a limit on inclusion depth when resolving nested directives. Specially crafted or overly complex schemas can cause excessive recursion during parsing. This may lead to stack exhaustion and application crashes, creating a denial-of-service risk.

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.

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."

A flaw was found in the libxslt library. The same memory field, psvi, is used for both stylesheet and input data, which can lead to type confusion during XML transformations. This vulnerability allows an attacker to crash the application or corrupt memory. In some cases, it may lead to denial of service or unexpected behavior.

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.

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.

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.

numbers.c in libxslt before 1.1.43 has a use-after-free because, in nested XPath evaluations, an XPath context node can be modified but never restored. This is related to xsltNumberFormatGetValue, xsltEvalXPathPredicate, xsltEvalXPathStringNs, and xsltComputeSortResultInternal.

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 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.

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

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.

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 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.

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.

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.

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

In libxml2 before 2.9.14, several buffer handling functions in buf.c (xmlBuf*) and tree.c (xmlBuffer*) don't check for integer overflows. This can result in out-of-bounds memory writes. Exploitation requires a victim to open a crafted, multi-gigabyte XML file. Other software using libxml2's buffer functions, for example libxslt through 1.1.35, is affected as well.

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

Use after free in Blink XSLT in Google Chrome prior to 91.0.4472.164 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.

A flaw was found in libxml2. Exponential entity expansion attack its possible bypassing all existing protection mechanisms and leading to denial of service.

There's a flaw in libxml2's xmllint in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by xmllint could trigger a use-after-free. The greatest impact of this flaw is to confidentiality, integrity, and availability.

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.

There's a flaw in libxml2 in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by an application linked with libxml2 could trigger a use-after-free. The greatest impact from this flaw is to confidentiality, integrity, and availability.

A vulnerability found in libxml2 in versions before 2.9.11 shows that it did not propagate errors while parsing XML mixed content, causing a NULL dereference. If an untrusted XML document was parsed in recovery mode and post-validated, the flaw could be used to crash the application. The highest threat from this vulnerability is to system availability.

GNOME project libxml2 v2.9.10 has a global buffer over-read vulnerability in xmlEncodeEntitiesInternal at libxml2/entities.c. The issue has been fixed in commit 50f06b3e.

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

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

Type confusion in xsltNumberFormatGetMultipleLevel prior to libxslt 1.1.33 could allow attackers to potentially exploit heap corruption via crafted XML data.