CVE-2026-79770: Nokogiri versions before 1.19.3 contain regular expression denial of service vulnerabilities in the CSS select

Q: How do I fix CVE-2026-79770?

nokogiri: upgrade to 1.19.3. Exact commands for each OS are on this page.

Q: Is CVE-2026-79770 being exploited?

CVE-2026-79770 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-79770 affect?

CVE-2026-79770 affects nokogiri. Severity is high (CVSS 7.5). 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 lik

Q: How urgent is CVE-2026-79770?

Priority 42/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2026-79770 is a high-severity flaw (CVSS 7.5) affecting nokogiri. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-1333
Published	2026-08-25
Last modified	2026-09-01

Publisher (CNA): VulnCheck · Vendor: nokogiri

Last updated 2026-09-01 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-25 16:17 UTCPublished CVE record published
2026-09-01 14:56 UTCUpdated Record last modified

nokogiri nokogiri UPGRADE

Affected: < 1.19.3

Fixed in: 1.19.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy nokogiri || rpm -q nokogiri || nokogiri --version

2. UPGRADE to 1.19.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nokogiri

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nokogiri

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-79770?

nokogiri: upgrade to 1.19.3. Exact commands for each OS are on this page.

Is CVE-2026-79770 being exploited?

CVE-2026-79770 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-79770 affect?

CVE-2026-79770 affects nokogiri. Severity is high (CVSS 7.5). 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 lik

How urgent is CVE-2026-79770?

Priority 42/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-57235 HIGH 8.2 UPGRADE Nokogiri is an open source XML and HTML library for the Ruby programming language
CVE-2026-57236 HIGH 8.2 UPGRADE Nokogiri is an open source XML and HTML library for the Ruby programming language
CVE-2026-57434 HIGH 7.5 UPGRADE Nokogiri is an open source XML and HTML library for the Ruby programming language
CVE-2026-57435 HIGH 7.5 UPGRADE Nokogiri is an open source XML and HTML library for the Ruby programming language
CVE-2026-57436 MEDIUM 5.3 UPGRADE Nokogiri is an open source XML and HTML library for the Ruby programming language

References

← Back to latest CVEs