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CVE-2026-45623
high
CVSS 7.5
Path Traversal in postcss (CVE-2026-45623)
Summary
path traversal in postcss (CVE-2026-45623). Confidential information can be exposed externally. Exploitable via ``PreviousMap``. Mitigation: upgrade to `8.5.12` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-45623** has been found in postcss.
Attackers can target a specific entry point like ``PreviousMap`` over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.5/10.
What to do: upgrade postcss to **8.5.12** or later.
If unsure, ask your IT team or search "postcss CVE-2026-45623" on the vendor's site.
CVE-2026-45623 (postcss) — CWE-22 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: `PreviousMap` / `PATH` / `JSON.parse` / `SyntaxError`
Patched: `8.5.12` — 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.
❓ What is the problem
**Path traversal** (CWE-22) exists in postcss. Attackers reach the vulnerable code path via ``PreviousMap`` without authentication.
📍 Affected scope
postcss — . Attack surface: `PreviousMap` / `PATH` / `JSON.parse` / `SyntaxError`.
🔥 Severity
Severity: High (CVSS 7.5/10). Confidential information can be exposed externally
🔧 How to fix
Update to **8.5.12**.
🛡️ Workaround
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'postcss' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'postcss' . | 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 `postcss` を grep し、稼働しているサービス・バージョンを把握する。
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6Apply patch patch
Upgrade postcss to 8.5.12ステージング環境で 8.5.12 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
npm
postcss
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.12"}]}]
References
- exploit 134c704f-9b21-4f2e-91b3-4a467353bcc0
- web https://github.com/postcss/postcss/commit/aaec7b78b3ce2792585b4b300ef1bd5dd5b3e8ad
- web https://github.com/postcss/postcss/commit/c64b7488d2731dfa16213739b42c34faf5a9eba3
- web https://github.com/postcss/postcss/releases/tag/8.5.12
- web https://github.com/advisories/GHSA-6g55-p6wh-862q