Vulnerability in css_parser (CVE-2026-44312)
Summary
Vulnerability in css_parser (CVE-2026-44312). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 1.22.0 or later.
Original description
The description as published by the source.
css_parser is a Ruby CSS parser. Prior to 2.1.0 and 1.22.0, the CSS Parser gem does not validate HTTPS connections, allowing a Man-in-the-Middle (MITM) attacker to inject or modify CSS content when stylesheets are loaded via HTTPS. The connection is established with OpenSSL::SSL::VERIFY_NONE, meaning any HTTPS certificate—even entirely untrusted—will be accepted without validation. This vulnerability is fixed in 2.1.0 and 1.22.0.
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-2026-44312 has been found in css_parser.
Risk of unauthorized operations or information disclosure. CVSS score: 5.8/10.
What to do: upgrade css_parser to 1.22.0 or later.
If unsure, ask your IT team or search "css_parser CVE-2026-44312" on the vendor's site.
CVE-2026-44312 (css_parser) — CWE-295 / CVSS v3 5.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 1.22.0 — 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-295) exists in css_parser.
Check the vendor advisory for the affected versions of css_parser.
Severity: Medium (CVSS 5.8/10). Risk of unauthorized operations or information disclosure.
Update to 1.22.0.
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 'css_parser' . 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
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1Identify exposure identify
grep -r 'css_parser' . | 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
css_parser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 css_parser to 1.22.0ステージング環境で 1.22.0 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-2026-44312 ruby-css-parser
- Ubuntu UBUNTU-CVE-2026-44312 ruby-css-parser
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- patch github.com
- patch github.com
- report github.com
- web github.com
- web github.com