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CVE

CVE-2026-40478

Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf
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CVE

CVE-2026-40478

Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf

Impact

A security bypass vulnerability exists in the expression execution mechanisms of Thymeleaf up to and including 3.1.3.RELEASE. 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).

Patches

This has been fixed in Thymeleaf 3.1.4.RELEASE.

Workarounds

No workaround is available beyond ensuring applications do not pass unvalidated user input directly to the template engine. Upgrading to 3.1.4.RELEASE is strongly recommended in any case.

Credits

Thanks to Dawid Bakaj (VIPentest.com) for responsible disclosure.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
-
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
C
H
U
-

Related Resources

No items found.

References

https://github.com/thymeleaf/thymeleaf/security/advisories/GHSA-xjw8-8c5c-9r79, https://github.com/thymeleaf/thymeleaf

Severity

9

CVSS Score
0
10

Basic Information

Ecosystem
Base CVSS
9
EPSS Probability
0%
EPSS Percentile
0%
Introduced Version
0
Fix Available
3.1.4.RELEASE

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