CVE-2026-79770
Nokogiri before 1.19.3 ReDoS via CSS selector tokenizer
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.
INFO
Published Date :
Aug. 25, 2026, 4:17 p.m.
Last Modified :
Sept. 1, 2026, 2:56 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 4.0 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Nokogiri to 1.19.3 or later.
- Avoid user input in CSS selectors.
- Sanitize CSS selectors before processing.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-79770.
| URL | Resource |
|---|---|
| https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-c4rq-3m3g-8wgx | Mitigation Vendor Advisory |
| https://www.vulncheck.com/advisories/nokogiri-before-redos-via-css-selector-tokenizer | Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-79770 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-79770
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-79770 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-79770 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Sep. 01, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:nokogiri:nokogiri:*:*:*:*:*:ruby:*:* versions up to (excluding) 1.19.3 Added Reference Type VulnCheck: https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-c4rq-3m3g-8wgx Types: Mitigation, Vendor Advisory Added Reference Type VulnCheck: https://www.vulncheck.com/advisories/nokogiri-before-redos-via-css-selector-tokenizer Types: Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 25, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-79770', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-25T16:10:25.348193Z'} -
New CVE Received by [email protected]
Aug. 25, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'sparklemotion', 'product': 'nokogiri', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '1.19.3', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '1.19.3', 'versionType': 'semver'}], 'packageURL': 'pkg:gem/nokogiri', 'defaultStatus': 'unaffected'}] Added 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-1333 Added Reference https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-c4rq-3m3g-8wgx Added Reference https://www.vulncheck.com/advisories/nokogiri-before-redos-via-css-selector-tokenizer