Use-After-Free in Nokogiri (CVE-2026-57437)
Summary
Vulnerability in Nokogiri (CVE-2026-57437). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 1.19.4 or later.
Original description
The description as published by the source.
Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, Nokogiri::XML::XPathContext did not keep its source document alive for garbage collection. If an XPathContext outlived its document and the document was collected, evaluating an XPath expression could read invalid memory and potentially segfault. This is only reachable when application code constructs an XPathContext directly and lets the document become unreachable while continuing to use the context. The normal Document#xpath, #css, and related search methods are not affected, and it is not triggerable by malicious document input. This vulnerability is fixed in 1.19.4.
Source: NIST National Vulnerability Database 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-2026-57437 has been found in Nokogiri.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade Nokogiri to 1.19.4 or later.
If unsure, ask your IT team or search "Nokogiri CVE-2026-57437" on the vendor's site.
CVE-2026-57437 (Nokogiri) — CWE-416 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 1.19.4 — 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.
Use-after-free (CWE-416) exists in Nokogiri.
Check the vendor advisory for the affected versions of Nokogiri.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 1.19.4.
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 1.19.4ステージング環境で 1.19.4 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。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-57437 ruby-nokogiri Fixed in: 1.19.4-r0
- Debian DEBIAN-CVE-2026-57437 ruby-nokogiri
- Ubuntu UBUNTU-CVE-2026-57437 ruby-nokogiri
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov