Vulnerability in nokogiri (CVE-2026-79772)
Summary
Vulnerability in nokogiri (CVE-2026-79772). Risk of unauthorized operations or information disclosure. Exploitable via xmlC14NExecute. Mitigation: upgrade to 1.19.1 or later.
Original description
The description as published by the source.
Summary
Nokogiri's CRuby extension fails to check the return value from xmlC14NExecute in the method Nokogiri::XML::Document#canonicalize and Nokogiri::XML::Node#canonicalize. When canonicalization fails, an empty string is returned instead of raising an exception. This incorrect return value may allow downstream libraries to accept invalid or incomplete canonicalized XML, which has been demonstrated to enable signature validation bypass in SAML libraries.
JRuby is not affected, as the Java implementation correctly raises RuntimeError on canonicalization failure.
Mitigation
Upgrade to Nokogiri >= 1.19.1.
Severity
The maintainers have assessed this as Medium severity. Nokogiri itself is a parsing library without a clear security boundary related to canonicalization, so the direct impact is that a method returns incorrect data on invalid input. However, this behavior was exploited in practice to bypass SAML signature validation in downstream libraries (see References).
Credit
This vulnerability was responsibly reported by HackerOne researcher d4d.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-79772 has been found in nokogiri.
Attackers can target a specific entry point like xmlC14NExecute over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade nokogiri to 1.19.1 or later.
If unsure, ask your IT team or search "nokogiri CVE-2026-79772" on the vendor's site.
CVE-2026-79772 (nokogiri) — CWE-252 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: xmlC14NExecute / RuntimeError / d4d
Patched: 1.19.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-252) exists in nokogiri. Attackers reach the vulnerable code path via xmlC14NExecute without authentication.
Check the vendor advisory for the affected versions of nokogiri. Attack surface: xmlC14NExecute / RuntimeError / d4d.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 1.19.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'nokogiri' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'nokogiri' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
nokogiriを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade nokogiri to 1.19.1ステージング環境で 1.19.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Ubuntu UBUNTU-CVE-2026-79772 ruby-nokogiri
References
- web github.com
- web nvd.nist.gov
- web vulncheck.com
- web github.com
- web github.com