CVE-2026-404789.1CriticalCWE-917

CVE-2026-40478: Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf

thymeleaf

Vendor fix available · Affected: thymeleaf · Exploitation: possible (1 to 10%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

1.1%probability of exploitation in the next 30 days

66th percentile

050100

Higher than 66% of scored CVEs

9.1CriticalCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products3

From the CVE record. A product or version that is not listed is unknown, not unaffected.

thymeleaf · thymeleaf< 3.1.4.RELEASE
thymeleaf · org.thymeleaf:thymeleaf-spring5< 3.1.4.RELEASE
thymeleaf · org.thymeleaf:thymeleaf-spring6< 3.1.4.RELEASE

On the Atlas

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Open the Atlas

Exploitation: Possible (1 to 10%). EPSS between 1% and 10%.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Improper Neutralization of Special Elements used in an Expression Language Statement · Command and Code Injection
Vendor: thymeleaf
Published: April 2026
Band: Possible (1 to 10%), April 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-40478 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.