{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.8.16"
              },
              {
                "introduced": "2.0.0-beta.1"
              },
              {
                "fixed": "2.0.0-rc.1"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "a2260e4a62f21591e1a9ae9b11c7db07c6507766"
            },
            {
              "introduced": "382991648c9db5d5e17476b55e4f9fe1cac1ea08"
            },
            {
              "fixed": "ebde06e404db0a5a52ff3507417037530c0371a8"
            }
          ],
          "repo": "https://github.com/flarum/framework",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-xjvc-pw2r-6878"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-22",
      "CWE-918"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41887.json"
  },
  "details": "Flarum is open-source forum software. Prior to versions 1.8.16 and 2.0.0-rc.1, Flarum's patch for CVE-2023-27577 restricted the @import and data-uri() LESS features in the custom_less setting, but the same restriction was never applied to other settings registered as LESS config variables (for example theme_primary_color and theme_secondary_color, as well as any key registered via Extend\\Settings::registerLessConfigVar()). Those values are interpolated verbatim into the LESS source at compile time, allowing an authenticated administrator to craft a theme-color value that injects an arbitrary @import directive into the compiled forum.css. Because the underlying LESS parser honours @import (inline) '\u003cpath\u003e', an attacker can read arbitrary files reachable by the PHP process (local file inclusion) or trigger outbound HTTP(S) requests (server-side request forgery). This issue has been patched in versions 1.8.16 and 2.0.0-rc.1.",
  "id": "CVE-2026-41887",
  "modified": "2026-08-04T11:30:50.521162151Z",
  "published": "2026-05-08T15:50:38.484Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/flarum/framework/releases/tag/v1.8.16"
    },
    {
      "type": "WEB",
      "url": "https://github.com/flarum/framework/releases/tag/v2.0.0-rc.1"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41887.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/flarum/framework/security/advisories/GHSA-xjvc-pw2r-6878"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41887"
    },
    {
      "type": "FIX",
      "url": "https://github.com/flarum/framework/commit/2d90a1f19f0e46f8c7e1b07c48ba74b5e38f8410"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Flarum: Path traversal in LESS parser via theme color settings (incomplete fix for CVE-2023-27577)"
}