Is CVE-2026-40478 in the CISA KEV catalog?

No. CVE-2026-40478 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-40478?

CVE-2026-40478 has a CVSS v3 base score of 9.0 (CRITICAL).

What is the EPSS score for CVE-2026-40478?

CVE-2026-40478 has an EPSS score of 0.58% (43th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-40478

CRITICAL

9.0

CVSS v3

NVD

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.

CWE-917 CWE-1336

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

0.58%probability of exploitation in 30 days

43rdpercentile

Moderate risk: more likely to be exploited than 43% of all known CVEs.

References

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

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-24.