Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-08-25T15:16:03 nokogiri: Nokogiri: Denial of Service via crafted CSS selectors 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CWE-1333

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.

A flaw was found in Nokogiri. A remote attacker can inject specially crafted CSS selectors into methods such as `Node#css` or `Node#at_css`. This injection can lead to regular expression denial of service (ReDoS) due to exponential regex backtracking, causing the application to become unresponsive.

A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in Nokogiri's CSS selector tokenizer. When processing untrusted user input passed to methods like Node#css, Node#at_css, or Searchable#search, an attacker can inject adversarial CSS selectors containing malicious string literals or identifiers. This triggers exponential regex backtracking within the parser, causing severe CPU exhaustion and leading to a Denial of Service (DoS) for the application thread. Do not pass untrusted user input directly into Nokogiri CSS search methods. If dynamic querying is necessary, sanitize input or restrict query parameter patterns before evaluation. Red Hat 3scale API Management Platform 2 Not affected 3scale-amp2/backend-rhel8 Red Hat 3scale API Management Platform 2 Not affected 3scale-amp2/system-rhel8 Red Hat 3scale API Management Platform 2 Not affected 3scale-amp2/system-rhel9 Red Hat 3scale API Management Platform 2 Not affected 3scale-amp2/toolbox-rhel9 Red Hat 3scale API Management Platform 2 Not affected 3scale-amp2/zync-rhel9 Red Hat Satellite 6 Not affected tfm-rubygem-amazing_print Red Hat Satellite 6 Not affected tfm-rubygem-graphql https://www.cve.org/CVERecord?id=CVE-2026-79770 https://nvd.nist.gov/vuln/detail/CVE-2026-79770 https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-c4rq-3m3g-8wgx https://www.vulncheck.com/advisories/nokogiri-before-redos-via-css-selector-tokenizer