CVE-2026-40477
9.0 · CRITICALOverview
CVE-2026-40477 is a critical-severity vulnerability affecting thymeleaf thymeleaf. It was published on April 17, 2026 and has a CVSS 3.1 base score of 9.0 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.0, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
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.
Remediation
Check the references section for vendor advisories and patches from thymeleaf. Update thymeleaf to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| thymeleaf | thymeleaf | >= 0, < 3.1.4 | Affected |
References
Frequently Asked Questions
What is CVE-2026-40477?
CVE-2026-40477 is a critical-severity vulnerability affecting thymeleaf thymeleaf. It was published on April 17, 2026 and has a CVSS 3.1 base score of 9.0 (CRITICAL).
How severe is CVE-2026-40477?
This vulnerability has a CVSS 3.1 base score of 9.0, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-40477?
Check the references section for vendor advisories and patches from thymeleaf. Update thymeleaf to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-40477?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-40477 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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