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CVE-2026-44897

Cross-Site Scripting (XSS) in mistune (CVE-2026-44897)

Summary

cross-site scripting in mistune (CVE-2026-44897). Risk of unauthorized operations or information disclosure. Exploitable via ``toc_1``. Mitigation: upgrade to `3.2.1` or later.

AI summary snake-internal / snake-material-v2

A vulnerability tracked as **CVE-2026-44897** has been found in mistune. Attackers can target a specific entry point like ``toc_1`` over the network to misuse the product. Risk of unauthorized operations or information disclosure. CVSS score: ?/10. What to do: upgrade mistune to **3.2.1** or later. If unsure, ask your IT team or search "mistune CVE-2026-44897" on the vendor's site.
CVE-2026-44897 (mistune) — CWE-79 / Attack surface: `toc_1` / `toc_2` / `heading_id` / `text` Patched: `3.2.1` — 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
**Cross-site scripting (XSS)** (CWE-79) exists in mistune. Attackers reach the vulnerable code path via ``toc_1`` without authentication.
📍 Affected scope
mistune — . Attack surface: `toc_1` / `toc_2` / `heading_id` / `text`.
🔥 Severity
Severity: ?. Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **3.2.1**.
🛡️ 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 'mistune' .` 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

  1. 1
    Identify exposure identify
    grep -r 'mistune' . | 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 `mistune` を grep し、稼働しているサービス・バージョンを把握する。

  2. 6
    Apply patch patch
    Upgrade mistune to 3.2.1

    ステージング環境で 3.2.1 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。

  3. 7
    Post-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

pip mistune
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.1"}]}]

References

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