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CVE-2026-41901
critical
CVSS 9.0
Vulnerability in org.thymeleaf:thymeleaf (CVE-2026-41901)
Summary
vulnerability in org.thymeleaf:thymeleaf (CVE-2026-41901). Successful exploitation can lead to full system takeover. Mitigation: upgrade to `3.1.5.RELEASE` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-41901** has been found in org.thymeleaf:thymeleaf.
Successful exploitation can lead to full system takeover. CVSS score: 9.0/10.
What to do: upgrade org.thymeleaf:thymeleaf to **3.1.5.RELEASE** or later.
If unsure, ask your IT team or search "org.thymeleaf:thymeleaf CVE-2026-41901" on the vendor's site.
CVE-2026-41901 (org.thymeleaf:thymeleaf) — CWE-917 / CVSS v3 9.0
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: `3.1.5.RELEASE` — apply immediately
Workaround: No workaround is available beyond ensuring applications do not pass unvalidated/unsanitized data directly to the template engine.
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
**A vulnerability** (CWE-917) exists in org.thymeleaf:thymeleaf.
📍 Affected scope
org.thymeleaf:thymeleaf — .
🔥 Severity
Severity: Critical (CVSS 9.0/10). Successful exploitation can lead to full system takeover
🔧 How to fix
Update to **3.1.5.RELEASE**.
🛡️ Workaround
Workaround: No workaround is available beyond ensuring applications do not pass unvalidated/unsanitized data directly to the template engine.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'org.thymeleaf:thymeleaf' .` 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 'org.thymeleaf:thymeleaf' . | 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 `org.thymeleaf:thymeleaf` 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
No workaround is available beyond ensuring applications do not pass unvalidated/unsanitized data directly to the template engine.パッチが適用されるまでの応急処置として、No workaround is available beyond ensuring applications do not pass unvalidated/unsanitized data directly to the template engine. 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 org.thymeleaf:thymeleaf to 3.1.5.RELEASEステージング環境で 3.1.5.RELEASE 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
maven
org.thymeleaf:thymeleaf
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.5.RELEASE"}]}]
maven
org.thymeleaf:thymeleaf-spring5
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.5.RELEASE"}]}]
maven
org.thymeleaf:thymeleaf-spring6
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.5.RELEASE"}]}]