thymeleaf/thymeleaf-spring5/thymeleaf-spring6 up to 3.1.3 expression language injection

Summaryinfo

A vulnerability labeled as problematic has been found in thymeleaf, thymeleaf-spring5 and thymeleaf-spring6 up to 3.1.3. This impacts an unknown function. The manipulation results in expression language injection. This vulnerability was named CVE-2026-40477. The attack may be performed from remote. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, was found in thymeleaf, thymeleaf-spring5 and thymeleaf-spring6 up to 3.1.3. Affected is an unknown part. The manipulation with an unknown input leads to a expression language injection vulnerability. CWE is classifying the issue as CWE-917. The product constructs all or part of an expression language (EL) statement in a framework such as a Java Server Page (JSP) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended EL statement before it is executed. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-40477 since 04/13/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. The technical details are unknown and an exploit is not available.

Upgrading to version 3.1.4 eliminates this vulnerability.

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Productinfo

Name

• thymeleaf
• thymeleaf-spring5
• thymeleaf-spring6

Version

• 3.1.0
• 3.1.1
• 3.1.2
• 3.1.3

Website

• Product: https://github.com/thymeleaf/thymeleaf/

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