CVE-2026-40478
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Summary
Thymeleaf is a server-side Java template engine for web and standalone environments. Versions 3.1.3.RELEASE and prior contain a security bypass vulnerability in the the expression execution mechanisms. Although the library provides mechanisms to prevent expression injection, it fails to properly neutralize specific syntax patterns that allow for the execution of unauthorized expressions. If an application developer passes unvalidated user input directly to the template engine, an unauthenticated remote attacker can bypass the library's protections to achieve Server-Side Template Injection (SSTI). This issue has ben fixed in version 3.1.4.RELEASE.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| thymeleaf | thymeleaf | < 3.1.4.RELEASE | affected |
| thymeleaf | org.thymeleaf:thymeleaf-spring5 | < 3.1.4.RELEASE | affected |
| thymeleaf | org.thymeleaf:thymeleaf-spring6 | < 3.1.4.RELEASE | affected |
Weaknesses
- CWE-917: CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
- CWE-1336: CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine
ADP Enrichment
CISA ADP Vulnrichment
- SSVC:
- Exploitation: none
- Automatable: no
- Technical Impact: total
thymeleaf: Thymeleaf: Server-Side Template Injection via expression execution bypass
Additional References
- https://access.redhat.com/security/cve/CVE-2026-40478
- https://bugzilla.redhat.com/show_bug.cgi?id=2459349
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40478.json
- https://access.redhat.com/errata/RHSA-2026:21772
References
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