Vulnerability in Nokogiri
CVE-2026-79770
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.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (40.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 40.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
Weakness classification (CWE)
References
- GitHub Security Advisory (GHSA-c4rq-3m3g-8wgx) (vendor-advisory, Mitigation, Vendor Advisory)
- VulnCheck Advisory: Nokogiri before 1.19.3 ReDoS via CSS selector tokenizer (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-79770?
- CVE-2026-79770 is a high-severity vulnerability in Nokogiri, classified under Inefficient Regular Expression Complexity. CVSS score: 7.5/10. Published 2026-08-25.
- How severe is CVE-2026-79770?
- High severity. CVSS v3 base score is 7.5 out of 10.