CVE-2026-40477

Summary

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.

Affected Software

VendorProductVersion RangeStatus
thymeleafthymeleaf< 3.1.4.RELEASEaffected
thymeleaforg.thymeleaf:thymeleaf-spring5< 3.1.4.RELEASEaffected
thymeleaforg.thymeleaf:thymeleaf-spring6< 3.1.4.RELEASEaffected

Weaknesses

  • CWE-917: CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
  • CWE-1336: CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

thymeleaf: Thymeleaf: Server-Side Template Injection via security bypass in expression execution

Additional References

References