{"cve":"CVE-2026-40478","nvd":{"published":"2026-04-17T22:16:33.650","modified":"2026-10-26T21:10:00.170","status":"Modified","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 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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H","score":9.0},"cwes":["CWE-917","CWE-1336"],"references":["https://github.com/thymeleaf/thymeleaf/security/advisories/GHSA-xjw8-8c5c-9r79","https://access.redhat.com/errata/RHSA-2026:21772","https://access.redhat.com/security/cve/CVE-2026-40478","https://bugzilla.redhat.com/show_bug.cgi?id=2459349","https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40478.json"],"products":["thymeleaf:thymeleaf"],"source":"nvd","synced_at":"2026-10-26T21:38:48.864438205+00:00"},"epss":{"cve":"CVE-2026-40478","score":0.01102,"percentile":0.65485,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-xjw8-8c5c-9r79","url":"https://osv.dev/vulnerability/GHSA-xjw8-8c5c-9r79","summary":"Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf","modified":"2026-05-05T16:12:18.897503Z","packages":[{"ecosystem":"Maven","name":"org.thymeleaf:thymeleaf","purl":"pkg:maven/org.thymeleaf/thymeleaf","ranges":["<3.1.4.RELEASE"],"fixed":["3.1.4.RELEASE"]},{"ecosystem":"Maven","name":"org.thymeleaf:thymeleaf-spring5","purl":"pkg:maven/org.thymeleaf/thymeleaf-spring5","ranges":["<3.1.4.RELEASE"],"fixed":["3.1.4.RELEASE"]},{"ecosystem":"Maven","name":"org.thymeleaf:thymeleaf-spring6","purl":"pkg:maven/org.thymeleaf/thymeleaf-spring6","ranges":["<3.1.4.RELEASE"],"fixed":["3.1.4.RELEASE"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}