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CVE

CVE-2026-40478

Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf
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CVE

CVE-2026-40478

Improper neutralization of specific syntax patterns for unauthorized expressions in 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 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.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
9
-
3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
C
H
U
-

Related Resources

No items found.

References

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40478.json, https://access.redhat.com/errata/RHSA-2026:21772, https://access.redhat.com/security/cve/CVE-2026-40478, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40478.json, https://github.com/thymeleaf/thymeleaf/security/advisories/GHSA-xjw8-8c5c-9r79, https://nvd.nist.gov/vuln/detail/CVE-2026-40478, https://bugzilla.redhat.com/show_bug.cgi?id=2459349

Severity

9

CVSS Score
0
10

Basic Information

Base CVSS
9
EPSS Probability
0.00864%
EPSS Percentile
0.55616%
Introduced Version
0
Fix Available
dca2346cf9071501ce498f5f38f93a0c6330f25c

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