XXE (XML External Entity) in nokogiri (CVE-2020-26247)
Summary
Vulnerability in nokogiri (CVE-2020-26247). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 1.11.0 or later.
Original description
The description as published by the source.
Nokogiri is a Rubygem providing HTML, XML, SAX, and Reader parsers with XPath and CSS selector support. In Nokogiri before version 1.11.0.rc4 there is an XXE vulnerability. XML Schemas parsed by Nokogiri::XML::Schema are trusted by default, allowing external resources to be accessed over the network, potentially enabling XXE or SSRF attacks. This behavior is counter to the security policy followed by Nokogiri maintainers, which is to treat all input as untrusted by default whenever possible. This is fixed in Nokogiri version 1.11.0.rc4.
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
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-2020-26247 has been found in nokogiri.
Risk of unauthorized operations or information disclosure.
What to do: upgrade nokogiri to 1.11.0 or later.
If unsure, ask your IT team or search "nokogiri CVE-2020-26247" on the vendor's site.
CVE-2020-26247 (nokogiri) — CWE-611
Attack vector: remote (network-reachable) / no user interaction
Patched: 1.11.0 — 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-611) exists in nokogiri.
Check the vendor advisory for the affected versions of nokogiri.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 1.11.0.
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 1.11.0ステージング環境で 1.11.0 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
- Debian DEBIAN-CVE-2020-26247 ruby-nokogiri Fixed in: 1.11.1+dfsg-1
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- advisory lists.debian.org
- advisory lists.debian.org
- advisory rubygems.org
- advisory security.gentoo.org
- package github.com
- patch github.com
- report hackerone.com
- web github.com
- web github.com