CVE-2026-40478

CriticalCVSS 9.0/10Last modified Aug 18, 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 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.

Metrics

CVSS 3.1 9.0/10CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Weakness enumeration

Affected software

No affected versions have been published.

Timeline

Published
Apr 17, 2026
Last modified
Aug 18, 2026
NVD status
Modified

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CVE-2026-40478: Critical severity, CVSS 9.0 | Vulnix