---
id: CVE-2026-79770
title: Nokogiri before 1.19.3 ReDoS via CSS selector tokenizer
summary: >-
  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 …
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-1333
vendor: sparklemotion
product: nokogiri
affected:
  - nokogiri < 1.19.3
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-08-25T16:10:25.348193Z'
published: '2026-08-25'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T15:51:27.061Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-79770'
references:
  - url: >-
      https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-c4rq-3m3g-8wgx
    label: GitHub Security Advisory (GHSA-c4rq-3m3g-8wgx)
  - url: >-
      https://www.vulncheck.com/advisories/nokogiri-before-redos-via-css-selector-tokenizer
    label: >-
      VulnCheck Advisory: Nokogiri before 1.19.3 ReDoS via CSS selector
      tokenizer
tags:
  - cve.org
epss: 0.00278
epssPercentile: 0.20572
ingestedAt: '2026-09-16T15:58:38.764Z'
---

## Overview

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.

## Affected

- `nokogiri < 1.19.3`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.