Critical

Improper restriction of the scope of accessible objects in Thymeleaf expressions

  • Disclosed: 15.04.2026
  • Updated: 11.10.2026 12:22

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 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).

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 Thomas Reburn (Praetorian) for responsible disclosure.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) org.thymeleaf:thymeleaf < 3.1.4.RELEASE 3.1.4.RELEASE
Java / Kotlin (Maven) org.thymeleaf:thymeleaf-spring5 < 3.1.4.RELEASE 3.1.4.RELEASE
Java / Kotlin (Maven) org.thymeleaf:thymeleaf-spring6 < 3.1.4.RELEASE 3.1.4.RELEASE

References

CVSS score 9/10
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Weakness (CWE)
CWE-1336, CWE-917
Platform
Java / Kotlin (Maven)
Package
org.thymeleaf:thymeleaf, org.thymeleaf:thymeleaf-spring5, org.thymeleaf:thymeleaf-spring6
Disclosed
15.04.2026
Updated
11.10.2026 12:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-r4v4-5mwr-2fwr - CC BY 4.0

Vulnerability history: org.thymeleaf:thymeleaf

All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries
3
First → latest
04.2026 05.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 3

Disclosures per year

  1. 2026: 3
  1. Critical · 9.0 CVE-2026-40478 < 3.1.4.RELEASE 3.1.4.RELEASE
  2. Improper restriction of the scope of accessible objects in Thymeleaf expressions this entry
    Critical · 9.0 CVE-2026-40477 < 3.1.4.RELEASE 3.1.4.RELEASE

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