High severity · published Aug 25, 2026
CVE-2026-79770
Nokogiri before 1.19.3 ReDoS via CSS selector tokenizer
7.5
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 42% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NO
nokogiri · sparklemotion
before 1.19.3 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-79770
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-79770
Mitigation
https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-c4rq-3m3g-8wgx
Third Party Advisory
https://www.vulncheck.com/advisories/nokogiri-before-redos-via-css-selector-tokenizer
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