CVE-2026-40478

CRITICAL EPSS 43.5%

Published Apr 17, 20262mo ago · Modified Jun 17, 20261w ago

9.0 CVSS 3.1

Critical

Published Apr 17, 2026 2mo ago

Last Modified Jun 17, 2026 1w ago

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.

CVSS Details

Base Score

9.0

Exploitability

2.2

Impact

6.0

Vector string

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

Attack Vector Network

Attack Complexity High

Privileges Required None

User Interaction None

Scope Changed

Confidentiality High

Integrity High

Availability High

Threat Intelligence

EPSS Exploit Probability

43.5% percentile

Exploit & Patch Status

No Known Exploit

No Patch Available

Weaknesses 2

CWE-1336

CWE-917

Affected Products 1

Vendor	Product	Version	Range
thymeleaf	thymeleaf	*	<3.1.4

References 1

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

Vendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.