CVE-2026-41901 — thymeleaf
CRITICALCVE-2026-41901 is a critical-severity (CVSS 9) Expression Language Injection vulnerability in org.thymeleaf:thymeleaf. A fix is available for org.thymeleaf:thymeleaf — see the affected versions and patch details below.
Thymeleaf: Improper recognition of unauthorized syntax patterns in sandboxed Thymeleaf expressions
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41901.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
org.thymeleaf:thymeleaf☕org.thymeleaf:thymeleaf-spring5☕org.thymeleaf:thymeleaf-spring6Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.thymeleaf:thymeleaf | all versions | 3.1.5.RELEASEorg.thymeleaf:thymeleaf:3.1.5.RELEASE |
| ☕Maven | org.thymeleaf:thymeleaf-spring5 | all versions | 3.1.5.RELEASEorg.thymeleaf:thymeleaf-spring5:3.1.5.RELEASE |
| ☕Maven | org.thymeleaf:thymeleaf-spring6 | all versions | 3.1.5.RELEASEorg.thymeleaf:thymeleaf-spring6:3.1.5.RELEASE |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.thymeleaf:thymeleaf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.thymeleaf:thymeleaf to 3.1.5.RELEASE or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41901 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Frequently Asked Questions
Is CVE-2026-41901 in your dependencies?
Find it across Maven, including transitive dependencies.