CVE-2026-79770Network attack vector

Application hang via CSS tokenizer backtracking

Published Aug 25, 2026 · Updated Aug 25, 2026

Regular expression denial of service in Nokogiri before 1.19.3 allows remote attackers to hang application threads via CSS selectors. The CSS selector tokenizer applies regexes with exponential backtracking to unterminated quoted strings and hex-escape-rich strings or identifiers. Exposure requires an application to pass attacker-controlled text into Nokogiri CSS parsing methods; developer-authored selectors do not expose the flaw.

CVSS severity8.7
High
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Regular expression denial of service in Nokogiri before 1.19.3 allows remote attackers to hang application threads via CSS selectors. The CSS selector tokenizer applies regexes with exponential backtracking to unterminated quoted strings and hex-escape-rich strings or identifiers. Exposure requires an application to pass attacker-controlled text into Nokogiri CSS parsing methods; developer-authored selectors do not expose the flaw.

The record

CVE
CVE-2026-79770
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
Sparkle Motion
Product
Nokogiri
Classifications
CWE-1333, CAPEC-492, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.19.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Sparkle Motion · Nokogiriversion=0 <1.19.3

Published CVSS scores

8.7VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5Nokogiri maintainersCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
CAPEC-492Regular Expression Exponential Blowup
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo