CVE-2026-40477
Improper restriction of the scope of accessible objects in Thymeleaf expressions
- State
- Published
- Severity
- 9.1 Critical
- Published
- Apr 17, 2026
- Updated
- Aug 17, 2026
- Reserved
- Apr 13, 2026
Description
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 expression execution mechanisms. Although the library provides mechanisms to prevent expression injection, it fails to properly restrict the scope of accessible objects, allowing specific potentially sensitive objects to be reached from within a template. 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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H | GitHub_M |
| 3.1 | 8.5 High | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H | redhat-SADP |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
thymeleafthymeleaf |
|
org.thymeleaf:thymeleaf-spring5thymeleaf |
|
org.thymeleaf:thymeleaf-spring6thymeleaf |
|
References
- https://github.com/thymeleaf/thymeleaf/security/advisories/GHSA-r4v4-5mwr-2fwr
- https://access.redhat.com/security/cve/CVE-2026-40477vdb-entry
- RHBZ#2459344issue-tracking
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40477.json
- https://access.redhat.com/errata/RHSA-2026:21772vendor-advisory
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