Vulnerability · Published Aug 25, 2026 · Assigned by VulnCheck

CVE-2026-79770Nokogiri before 1.19.3 ReDoS via CSS selector tokenizer

High 7.5

In plain English

A high-severity regular-expression denial of service in nokogiri from sparklemotion. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.5%top 57.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	ruby-nokogiri	no fix listed	DEBIAN-CVE-2026-79770
Debian:13	ruby-nokogiri	no fix listed	DEBIAN-CVE-2026-79770
Debian:14	ruby-nokogiri	1.19.3+dfsg-1	DEBIAN-CVE-2026-79770
RubyGems	nokogiri	1.19.3	GHSA-c4rq-3m3g-8wgx
Ubuntu:24.04:LTS	ruby-nokogiri	no fix listed	UBUNTU-CVE-2026-79770
Ubuntu:26.04:LTS	ruby-nokogiri	no fix listed	UBUNTU-CVE-2026-79770

Affected products (as reported)

Vendor	Product	Versions
sparklemotion	nokogiri	0 – before 1.19.3

Weakness: CWE-1333 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

GitHub Security Advisory (GHSA-c4rq-3m3g-8wgx) vendor-advisory
VulnCheck Advisory: Nokogiri before 1.19.3 ReDoS via CSS selector tokenizer third-party-advisory