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CVE-2026-40477

thymeleaf org.thymeleaf:thymeleaf-spring5

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…

CheckOps priority index
4.9/10 Patch within 7 days
Severity9.1
Probability0.1
Exploitation2/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 0.85% higher than 58.2% of CVEs
CVSS 3.1 9.1 AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:
Exploited for 24 days 10 Oct 2026
Fixed packages 0 / 0 in open source registries

Exploitation probability EPSS · FIRST

05010025 Sep05 Oct15 Oct24 Oct02 Nov
EPSS probability (%)Percentile among all CVEs

Exploitation signals 2 / 5

  • KEV catalog (CISA)no
  • Exploited in EUVD (ENISA)10 Oct 2026
  • Used by ransomwareno
  • EPSS above 10 %0.85%
  • No account, over the networkyes

What to do

Fix

Apply the vendor’s fix as soon as it is available.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

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 products

org.thymeleaf:thymeleaf-spring5org.thymeleaf:thymeleaf-spring6thymeleaf
Affected versions
  • < 3.1.4.RELEASE

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

  1. Published

  2. Exploitation reported (ENISA)

References

Other exploited vulnerabilities from the same vendor

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Sources: CISA KEV · ENISA EUVD · FIRST EPSS · OSV. Public data aggregated by CheckOps, updated automatically. Source texts remain the property of their authors. All exploited vulnerabilities