Regular Expression Vulnerability in Nokogiri Affecting String-Literal and Identifier Tokenization
CVE-2026-79770

8.7HIGH

Key Information:

Vendor

Sparklemotion

Status
Nokogiri
Vendor
CVE Published:
25 August 2026

What is CVE-2026-79770?

Nokogiri versions prior to 1.19.3 are susceptible to vulnerabilities in the CSS selector tokenizer, which can be exploited by attackers through crafted CSS selectors. This can lead to severe performance degradation by causing exponential backtracking during regex evaluation, potentially disrupting service availability. Methods affected include Node#css, Node#at_css, and Searchable#search.

Affected Version(s)

nokogiri 0 < 1.19.3

nokogiri 1.19.3

References

https://github.com/sparklemotion/nokogiri/security/adviso...
vendor-advisory
https://www.vulncheck.com/advisories/nokogiri-before-redo...
third-party-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

colby-swandale
flavorjones
.