GHSA-XJW8-8C5C-9R79

Vulnerability from github – Published: 2026-04-15 19:46 – Updated: 2026-04-15 19:46
VLAI?
Summary
Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf
Details

Impact

A security bypass vulnerability exists in the expression execution mechanisms of Thymeleaf up to and including 3.1.3.RELEASE. 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).

Patches

This has been fixed in Thymeleaf 3.1.4.RELEASE.

Workarounds

No workaround is available beyond ensuring applications do not pass unvalidated user input directly to the template engine. Upgrading to 3.1.4.RELEASE is strongly recommended in any case.

Credits

Thanks to Dawid Bakaj (VIPentest.com) for responsible disclosure.

Severity ?
9.0 (Critical)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.1.3.RELEASE"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "org.thymeleaf:thymeleaf"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.4.RELEASE"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.1.3.RELEASE"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "org.thymeleaf:thymeleaf-spring5"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.4.RELEASE"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.1.3.RELEASE"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "org.thymeleaf:thymeleaf-spring6"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.4.RELEASE"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40478"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1336",
      "CWE-917"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-15T19:46:23Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Impact\nA security bypass vulnerability exists in the expression execution mechanisms of Thymeleaf up to and including 3.1.3.RELEASE. 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\u0027s protections to achieve Server-Side Template Injection (SSTI).\n\n### Patches\nThis has been fixed in Thymeleaf 3.1.4.RELEASE.\n\n### Workarounds\nNo workaround is available beyond ensuring applications do not pass unvalidated user input directly to the template engine. Upgrading to 3.1.4.RELEASE is strongly recommended in any case.\n\n### Credits\nThanks to Dawid Bakaj (VIPentest.com) for responsible disclosure.",
  "id": "GHSA-xjw8-8c5c-9r79",
  "modified": "2026-04-15T19:46:23Z",
  "published": "2026-04-15T19:46:23Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/thymeleaf/thymeleaf/security/advisories/GHSA-xjw8-8c5c-9r79"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/thymeleaf/thymeleaf"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Improper neutralization of specific syntax patterns for unauthorized expressions in Thymeleaf"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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