Vulnerability · Published May 12, 2026 · Assigned by GitHub_M
CVE-2026-41901Thymeleaf: Improper recognition of unauthorized syntax patterns in sandboxed Thymeleaf expressions
Critical 9.0
In plain English
A critical-severity expression language injection in thymeleaf from thymeleaf. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official description
Thymeleaf is a server-side Java template engine for web and standalone environments. Prior to 3.1.5.RELEASE, a security bypass vulnerability exists in the expression execution mechanisms of Thymeleaf. 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). This vulnerability is fixed in 3.1.5.RELEASE.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Maven | org.thymeleaf:thymeleaf | 3.1.5.RELEASE | GHSA-c9ph-gxww-7744 |
| Maven | org.thymeleaf:thymeleaf-spring5 | 3.1.5.RELEASE | GHSA-c9ph-gxww-7744 |
| Maven | org.thymeleaf:thymeleaf-spring6 | 3.1.5.RELEASE | GHSA-c9ph-gxww-7744 |
Affected products (as reported)
Weakness: CWE-917, CWE-1336 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
References
- https://github.com/thymeleaf/thymeleaf/security/advisories/GHSA-c9ph-gxww-7744 x_refsource_CONFIRM