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CVE-2026-41591
medium
CVSS 6.4
Cross-Site Scripting (XSS) in marko (CVE-2026-41591)
Summary
cross-site scripting in marko (CVE-2026-41591). Risk of unauthorized operations or information disclosure. Exploitable via ``_escape_script``. Mitigation: upgrade to `5.38.36` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-41591** has been found in marko.
Attackers can target a specific entry point like ``_escape_script`` over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.4/10.
What to do: upgrade marko to **5.38.36** or later.
If unsure, ask your IT team or search "marko CVE-2026-41591" on the vendor's site.
CVE-2026-41591 (marko) — CWE-79 / CVSS v3 6.4
Attack vector: remote (network-reachable) / no user interaction
Attack surface: `_escape_script` / `_escape_style` / `_escape_comment`
Patched: `5.38.36` — apply immediately
Workaround: Upgrade to the patched release.
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
**Cross-site scripting (XSS)** (CWE-79) exists in marko. Attackers reach the vulnerable code path via ``_escape_script`` without authentication.
📍 Affected scope
marko — . Attack surface: `_escape_script` / `_escape_style` / `_escape_comment`.
🔥 Severity
Severity: Medium (CVSS 6.4/10). Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **5.38.36**.
🛡️ Workaround
Workaround: Upgrade to the patched release.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'marko' .` 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 'marko' . | 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 `marko` 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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5Apply temporary workaround mitigate
Upgrade to the patched release.パッチが適用されるまでの応急処置として、Upgrade to the patched release. を実施。回避策の副作用 (機能低下) を確認した上で。
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6Apply patch patch
Upgrade marko to 5.38.36ステージング環境で 5.38.36 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
marko
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"5.38.36"}]}]
npm
@marko/runtime-tags
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"6.0.164"}]}]