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.
Original description
The description as published by the source.
Impact
A security bypass vulnerability exists in the expression execution mechanisms of Thymeleaf up to and including 3.1.4.RELEASE. Although the library provides mechanisms to avoid the execution of potentially dangerous expressions in some specific sandboxed (restricted) contexts, it fails to properly neutralize specific constructs that allow this kind of expressions to be executed. If an application developer passes to the template engine unsanitized variables that contain such expressions, and these values are used in sandboxed contexts inside the templates, these expressions can be executed achieving Server-Side Template Injection (SSTI).
Patches
This has been fixed in Thymeleaf 3.1.5.RELEASE. All users are advised to upgrade immediately.
Workarounds
No workaround is available beyond ensuring applications do not pass unvalidated/unsanitized data directly to the template engine. Upgrading to 3.1.5.RELEASE is strongly recommended in any case.
Source: NIST National Vulnerability Database NVD GitHub Advisory
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-2026-41901 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-1336 / 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.
A vulnerability (CWE-1336) exists in org.thymeleaf:thymeleaf.
Check the vendor advisory for the affected versions of org.thymeleaf:thymeleaf.
Severity: Critical (CVSS 9.0/10). Successful exploitation can lead to full system takeover.
Update to 3.1.5.RELEASE.
Workaround: No workaround is available beyond ensuring applications do not pass unvalidated/unsanitized data directly to the template engine.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies 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
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで org.thymeleaf:thymeleaf を使っているサービスとバージョンを洗い出す。
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2Apply 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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3Apply 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を含めること。
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4Post-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
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com