nokogiri CVE Vulnerabilities & Metrics

Nokogiri versions before 1.19.1 fail to check the return value from xmlC14NExecute in the canonicalize method, returning an empty string on failure instead of raising an exception. Attackers can exploit this to bypass signature validation in downstream SAML libraries by providing invalid canonicalized XML that is incorrectly accepted as valid.

Nokogiri versions before 1.19.3 contain a memory leak in the XSLT Stylesheet transform method when processing Ruby strings containing null bytes. Attackers can exploit this by passing attacker-controlled input with null bytes to transform parameters, causing heap allocations to leak and enabling denial of service against long-running processes.

Nokogiri versions before 1.19.3 contain regular expression denial of service vulnerabilities in the CSS selector tokenizer affecting string-literal and identifier tokenization. Attackers can inject adversarial CSS selectors into methods like Node#css, Node#at_css, and Searchable#search to cause exponential regex backtracking and denial of service.

Nokogiri before 1.18.3 contains a stack buffer overflow vulnerability in libxml2 when reporting DTD validation errors with long QName prefixes, and a use-after-free vulnerability during validation against untrusted XML Schemas. Attackers can trigger these vulnerabilities by providing malicious DTD content or untrusted XSD files to cause denial of service or potential code execution.

Nokogiri before 1.18.4 bundles a vulnerable version of libxslt (prior to 1.1.43) that contains two use-after-free vulnerabilities: CVE-2025-24855 (use-after-free of the XPath context node due to xsltEvalXPathStringNs leaking xpathCtxt->node) and CVE-2024-55549 (use-after-free related to excluded result prefixes/namespaces). Processing crafted XSLT can trigger memory corruption. Nokogiri 1.18.4 upgrades the bundled libxslt to 1.1.43 to resolve these issues.

Nokogiri before 1.18.8 packages a vulnerable version of libxml2 (before 2.13.8) that contains a heap-based buffer under-read (CVE-2025-32415) in the xmlSchemaIDCFillNodeTables function in xmlschemas.c. The issue can be triggered when validating against an untrusted XML Schema, or when validating untrusted documents against trusted schemas that use xsd:keyref in combination with recursively defined types that have additional identity constraints. Upstream and MITRE rate this issue as low severity.

Nokogiri before 1.15.6 and 1.16.x before 1.16.2 (CRuby, when using the packaged libxml2) is affected by a use-after-free vulnerability in libxml2 (CVE-2024-25062) in the xmlTextReader module, which underlies Nokogiri::XML::Reader. When using the XML Reader interface with DTD validation and XInclude expansion enabled, processing a crafted XML document can lead to an xmlValidatePopElement use-after-free. Nokogiri 1.15.6 and 1.16.2 resolve this by upgrading the packaged libxml2 to 2.11.7 and 2.12.5 respectively. JRuby and installations using system libxml2 are not affected.

Nokogiri versions before 1.16.5 bundle libxml2 2.12.6, which is affected by CVE-2024-34459 in libxml2's xmllint tool. Nokogiri 1.16.5 upgrades the bundled libxml2 to 2.12.7 to address this. Per the maintainers, there is no impact to Nokogiri users because Nokogiri does not provide or expose the xmllint tool where the issue occurs.

Nokogiri before 1.14.3 (CRuby implementation only, when using the packaged libxml2) bundles libxml2 v2.10.3, which is vulnerable to NULL pointer dereferences in XML Schema processing (xmlSchemaFixupComplexType, CVE-2023-28484, and xmlSchemaCheckCOSSTDerivedOK). An attacker who supplies a crafted/malformed XML schema can cause libxml2 to dereference a NULL pointer and potentially segfault, resulting in a denial of service. Nokogiri 1.14.3 upgrades the packaged libxml2 to v2.10.4 to resolve these issues.

Nokogiri before 1.13.2 (CRuby, when using packaged libraries) ships vendored libxml2 2.9.12 and libxslt 1.1.34, which are affected by two upstream CVEs. Via CVE-2021-30560 in libxslt, an application transforming XML with untrusted XSL stylesheets is vulnerable to a denial-of-service attack. Via CVE-2022-23308 in libxml2, an application parsing an untrusted document with parse option DTDVALID set to true and NOENT set to false may be vulnerable to denial of service, memory disclosure, or code execution. Nokogiri 1.13.2 upgrades vendored libxml2 to 2.9.13 and libxslt to 1.1.35.

Nokogiri versions before 1.13.5 contain an integer overflow vulnerability in packaged libxml2 buffer handling functions that allows attackers to cause out-of-bounds memory writes. Attackers can exploit this by crafting multi-gigabyte XML files to trigger buffer overflows resulting in information disclosure, data modification, or denial of service.

Nokogiri before 1.13.9 (CRuby implementation using packaged libraries) bundles libxml2 v2.9.14, which is affected by CVE-2022-40304 (data corruption / double-free from an entity reference cycle when entity content is allocated from a dict) and CVE-2022-40303 (integer overflows when parsing with XML_PARSE_HUGE). Nokogiri 1.13.9 upgrades the packaged libxml2 to v2.10.3 to address these issues. Processing crafted XML input may lead to denial of service or memory corruption. (The advisory also references CVE-2022-2309, a NULL pointer dereference via iterwalk/canonicalize, which maintainers determined does not affect Nokogiri users.)

Nokogiri before 1.11.4 (CRuby implementation only, when the packaged/vendored libxml2 is used) bundles libxml2 2.9.10, which is affected by multiple vulnerabilities addressed in libxml2 2.9.12, including a memory leak in xmlSchemaValidateStream (CVE-2019-20388), a global buffer over-read in xmlEncodeEntitiesInternal (CVE-2020-24977), a heap-based buffer overflow (CVE-2021-3517), and an out-of-bounds read (CVE-2021-3518). Processing crafted XML documents may lead to denial of service, information disclosure, or memory corruption.

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, XInclude substitution performed by Nokogiri::XML::Node#do_xinclude replaced each <xi:include> in place, freeing the include node along with its children (such as <xi:fallback> and its descendants) and any namespaces declared on them. If an application had already exposed one of those nodes or namespaces to Ruby, the corresponding Ruby object was left pointing at freed memory. Using the object could result in invalid reads or writes to memory. This vulnerability is fixed in 1.19.4.

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, Nokogiri::XML::XPathContext did not keep its source document alive for garbage collection. If an XPathContext outlived its document and the document was collected, evaluating an XPath expression could read invalid memory and potentially segfault. This is only reachable when application code constructs an XPathContext directly and lets the document become unreachable while continuing to use the context. The normal Document#xpath, #css, and related search methods are not affected, and it is not triggerable by malicious document input. This vulnerability is fixed in 1.19.4.

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, Nokogiri::XML::Document#root= validated only that the new root was a Nokogiri::XML::Node, allowing a DTD node to be set as the document root. The result is a heap use-after-free during garbage collection or finalization, leading to an invalid memory read or potentially a segfault. This vulnerability is fixed in 1.19.4.

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, Nokogiri’s CRuby native extension could leave a Ruby wrapper pointing to freed memory when replacing the value of an XML attribute. If Ruby code had already accessed an attribute child node, Nokogiri::XML::Attr#value= could free the underlying native child node while the wrapper remained reachable through the document node cache. A later use of the freed child node or a Ruby GC mark could dereference an invalid pointer, causing an invalid read and a possible segfault. This vulnerability is fixed in 1.19.4.

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, Nokogiri contains a bug when calling certain methods on allocated-but-uninitialized native wrapper classes that inherit from Nokogiri::XML::Node. This caused a NULL pointer dereference that could crash the process. This vulnerability is fixed in 1.19.4.

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, calling Document#encoding= with an invalid encoding (e.g., a non-string, or a string containing a null byte) raises an exception, but only after freeing the document's current encoding string without replacing it. The document is left referencing freed memory, so the next call to Document#encoding reads invalid memory, which can cause a segfault or leak freed bytes into a Ruby String. Affects the CRuby (libxml2) implementation only; JRuby is not affected. This vulnerability is fixed in 1.19.4.

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, Nokogiri::XML::NodeSet#[] (and its alias #slice) checked the requested index against the node set's bounds using a 32-bit-truncated copy of the index. A large negative index could pass the check and then be used at full width, reading outside the node set's storage. On CRuby this is an out-of-bounds read that typically crashes the process; on JRuby it is not memory-unsafe but returns an incorrect node. This vulnerability is fixed in 1.19.4.

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, the NONET parse option, which Nokogiri turns on by default for Nokogiri::XML::Schema (see CVE-2020-26247), was not correctly enforced on the JRuby implementation. As a result, a schema parsed with default options could still cause external resources to be fetched over the network, potentially enabling SSRF or XXE attacks. This vulnerability is fixed in 1.19.4.

Nokogiri is an open source XML and HTML library for the Ruby programming language. Nokogiri `1.13.8` and `1.13.9` fail to check the return value from `xmlTextReaderExpand` in the method `Nokogiri::XML::Reader#attribute_hash`. This can lead to a null pointer exception when invalid markup is being parsed. For applications using `XML::Reader` to parse untrusted inputs, this may potentially be a vector for a denial of service attack. Users are advised to upgrade to Nokogiri `>= 1.13.10`. Users may be able to search their code for calls to either `XML::Reader#attributes` or `XML::Reader#attribute_hash` to determine if they are affected.

Nokogiri is an open source XML and HTML library for Ruby. Nokogiri prior to version 1.13.6 does not type-check all inputs into the XML and HTML4 SAX parsers, allowing specially crafted untrusted inputs to cause illegal memory access errors (segfault) or reads from unrelated memory. Version 1.13.6 contains a patch for this issue. As a workaround, ensure the untrusted input is a `String` by calling `#to_s` or equivalent.

Nokogiri is an open source XML and HTML library for Ruby. Nokogiri `< v1.13.4` contains an inefficient regular expression that is susceptible to excessive backtracking when attempting to detect encoding in HTML documents. Users are advised to upgrade to Nokogiri `>= 1.13.4`. There are no known workarounds for this issue.

zlib before 1.2.12 allows memory corruption when deflating (i.e., when compressing) if the input has many distant matches.

Nokogiri is a Rubygem providing HTML, XML, SAX, and Reader parsers with XPath and CSS selector support. In Nokogiri v1.12.4 and earlier, on JRuby only, the SAX parser resolves external entities by default. Users of Nokogiri on JRuby who parse untrusted documents using any of these classes are affected: Nokogiri::XML::SAX::Parse, Nokogiri::HTML4::SAX::Parser or its alias Nokogiri::HTML::SAX::Parser, Nokogiri::XML::SAX::PushParser, and Nokogiri::HTML4::SAX::PushParser or its alias Nokogiri::HTML::SAX::PushParser. JRuby users should upgrade to Nokogiri v1.12.5 or later to receive a patch for this issue. There are no workarounds available for v1.12.4 or earlier. CRuby users are not affected.

Nokogiri is a Rubygem providing HTML, XML, SAX, and Reader parsers with XPath and CSS selector support. In Nokogiri before version 1.11.0.rc4 there is an XXE vulnerability. XML Schemas parsed by Nokogiri::XML::Schema are trusted by default, allowing external resources to be accessed over the network, potentially enabling XXE or SSRF attacks. This behavior is counter to the security policy followed by Nokogiri maintainers, which is to treat all input as untrusted by default whenever possible. This is fixed in Nokogiri version 1.11.0.rc4.

Nokogiri before 1.5.4 is vulnerable to XXE attacks

Nokogiri gem 1.5.x and 1.6.x has DoS while parsing XML entities by failing to apply limits

Nokogiri gem 1.5.x has Denial of Service via infinite loop when parsing XML documents

A command injection vulnerability in Nokogiri v1.10.3 and earlier allows commands to be executed in a subprocess via Ruby's `Kernel.open` method. Processes are vulnerable only if the undocumented method `Nokogiri::CSS::Tokenizer#load_file` is being called with unsafe user input as the filename. This vulnerability appears in code generated by the Rexical gem versions v1.0.6 and earlier. Rexical is used by Nokogiri to generate lexical scanner code for parsing CSS queries. The underlying vulnerability was addressed in Rexical v1.0.7 and Nokogiri upgraded to this version of Rexical in Nokogiri v1.10.4.