{"basis":"claimed","id":"CVE-2026-40478","name":"Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf","vendorProject":"thymeleaf","product":"thymeleaf","publishedAt":"2026-04-17","cvss":{"score":9.1,"severity":"CRITICAL","version":"3.1"},"exploited":null,"epss":{"score":0.01102,"percentile":0.65717,"date":"2026-11-02"},"coverage":{"cloudflare":{"status":"none","firstOn":null,"daysToRule":null},"aws":{"status":"none","firstOn":null,"daysToRule":null},"azure":{"status":"none","firstOn":null,"daysToRule":null},"google":{"status":"none","firstOn":null,"daysToRule":null},"fastly":{"status":"no_history","firstOn":null,"daysToRule":null},"f5":{"status":"rule","firstOn":"2026-07-07","daysToRule":81},"akamai":{"status":"no_source","firstOn":null,"daysToRule":null},"crs":{"status":"none","firstOn":null,"daysToRule":null}},"title":"Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf","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.","cwes":["CWE-917","CWE-1336"],"vendors":[{"vendor":"cloudflare","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"aws","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"azure","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"google","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"fastly","status":"no_history","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"f5","status":"rule","basis":"claimed","firstOn":"2026-07-07","firstIsNew":true,"daysToRule":81,"daysAtMost":null,"freePlan":false,"claims":[{"id":"43d62ad75877c5990e47eb0b09dccdd0010f97718d91d28891d1c77e2db05e5e","cve_id":"CVE-2026-40478","vendor":"f5","product":"Attack signatures","rule_id":"200204074","rule_name":"Thymeleaf Remote Code Execution (1)","change":"new","default_action":null,"published_on":"2026-07-07","source_url":"https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog","source_title":"F5 Distributed Cloud attack signatures changelog","excerpt":"Added: signature 200204074 \"Thymeleaf Remote Code Execution (1)\" (Server Side Code Injection, risk High), systems: Other Web Server. References: CVE-2026-40478.","first_seen_at":"2026-11-02T21:00:24.865Z"},{"id":"583fdf1d2301eef0e212d485893df5db3e603d5089bc569ff66d55bef42f1a6a","cve_id":"CVE-2026-40478","vendor":"f5","product":"Attack signatures","rule_id":"200204075","rule_name":"Thymeleaf Remote Code Execution (2)","change":"new","default_action":null,"published_on":"2026-07-07","source_url":"https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog","source_title":"F5 Distributed Cloud attack signatures changelog","excerpt":"Added: signature 200204075 \"Thymeleaf Remote Code Execution (2)\" (Server Side Code Injection, risk High), systems: Other Web Server. References: CVE-2026-40478.","first_seen_at":"2026-11-02T21:00:24.865Z"}]},{"vendor":"akamai","status":"no_source","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"crs","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]}],"updatedAt":"2026-11-02T21:17:16.726Z","cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H","ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total"},"measured":[],"social":{"total":0,"first_seen":null,"daily":[{"day":"2026-10-21","posts":0},{"day":"2026-10-22","posts":0},{"day":"2026-10-23","posts":0},{"day":"2026-10-24","posts":0},{"day":"2026-10-25","posts":0},{"day":"2026-10-26","posts":0},{"day":"2026-10-27","posts":0},{"day":"2026-10-28","posts":0},{"day":"2026-10-29","posts":0},{"day":"2026-10-30","posts":0},{"day":"2026-10-31","posts":0},{"day":"2026-11-01","posts":0},{"day":"2026-11-02","posts":0},{"day":"2026-11-03","posts":0}],"top_posts":[],"exploit_repositories":[]}}