{"id":"CVE-2026-41887","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-41887","generatedAt":"2026-10-27T23:58:03.989Z","title":"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.","description":"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) '<path>', 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.","published":"2026-05-08T17:16:31.000Z","lastModified":"2026-10-26T18:10:00.000Z","status":"Deferred","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":4.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N"},"cwe":["CWE-22","CWE-918"],"affected":[],"epss":{"score":0.00404,"percentile":0.34381,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.40%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://github.com/flarum/framework/commit/2d90a1f19f0e46f8c7e1b07c48ba74b5e38f8410","source":"security-advisories@github.com"},{"url":"https://github.com/flarum/framework/releases/tag/v1.8.16","source":"security-advisories@github.com"},{"url":"https://github.com/flarum/framework/releases/tag/v2.0.0-rc.1","source":"security-advisories@github.com"},{"url":"https://github.com/flarum/framework/security/advisories/GHSA-xjvc-pw2r-6878","source":"security-advisories@github.com"},{"url":"https://github.com/flarum/framework/security/advisories/GHSA-xjvc-pw2r-6878","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-41887","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}