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Vulnerabilities

Vulnerability · CVE-2026-40477

Thymeleaf is a server-side Java template engine for web and standalone environments.

Published Apr 17, 2026 · catalog updated Aug 4, 2026 · Thymeleaf is a server-side

Check if you run it

No confirmed exploitation is on record for CVE-2026-40477. EPSS is 0.94%. Act only if a listed version of Thymeleaf is a server-side is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Thymeleaf is a server-side).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.94%
Remediation
Advisory link
Affected products
cpe thymeleaf/thymeleaf

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe thymeleaf/thymeleafversion unspecified

How to fix CVE-2026-40477

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-40477. EPSS is 0.94%. Act only if a listed version of Thymeleaf is a server-side is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine; CWE-917: Expression Language Injection. EPSS 0.94%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 17, 2026 · NIST NVD

    Detected

    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 fro

  2. Aug 4, 2026 · NIST NVD

    Updated

    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 fro

Sources

  • CVE.orgVulnerability recordCVE-2026-40477

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-40477

    30-day exploitation probability 0.9%

    first.org
  • NIST NVDVulnerability recordCVE-2026-40477

    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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.