Vulnerability in nokogiri (CVE-2026-79771)
Summary
Vulnerability in nokogiri (CVE-2026-79771). Risk of unauthorized operations or information disclosure. Exploitable via XSLT.transform. Mitigation: upgrade to 1.19.3 or later.
Original description
The description as published by the source.
Summary
Nokogiri's Nokogiri::XSLT::Stylesheet#transform leaks a small heap allocation when passed a Ruby string parameter containing a null byte.
For applications that pass attacker-controlled input through XSLT.transform parameters, this may be a vector for a denial of service attack against long-running processes.
Mitigation
Upgrade to Nokogiri >= 1.19.3.
Users may also be able to mitigate this issue without upgrading by validating untrusted transform parameters before passing them to Nokogiri::XSLT::Stylesheet#transform.
Severity
The Nokogiri maintainers have evaluated this as Moderate Severity, CVSS 5.3.
Each leaked allocation is approximately 24–32 bytes, so meaningful memory growth requires sustained attacker-controlled traffic at high call rates. The bug does not cause memory corruption, information disclosure, or any change in the behavior of the transform itself, and the string-handling exception is raised as expected.
Applications that do not pass raw attacker-controlled bytes to XSLT parameters are unlikely to be affected in practice.
Resources
Credit
This vulnerability was responsibly reported by @Captainjack-kor.
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-2026-79771 has been found in nokogiri.
Attackers can target a specific entry point like XSLT.transform 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 1.19.3 or later.
If unsure, ask your IT team or search "nokogiri CVE-2026-79771" on the vendor's site.
CVE-2026-79771 (nokogiri) — CWE-401 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: XSLT.transform
Patched: 1.19.3 — 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-401) exists in nokogiri. Attackers reach the vulnerable code path via XSLT.transform without authentication.
Check the vendor advisory for the affected versions of nokogiri. Attack surface: XSLT.transform.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 1.19.3.
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 1.19.3ステージング環境で 1.19.3 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
References
- web github.com
- web nvd.nist.gov
- web vulncheck.com
- web github.com
- web github.com