CVE-2026-41887

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{"affected": [{"affectedData": [{"product": "framework", "vendor": "flarum", "versions": [{"status": "affected", "version": "< 1.8.16"}, {"status": "affected", "version": ">= 2.0.0-beta.1, < 2.0.0-rc.1"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Flarum es un software de foro de c\u00f3digo abierto. Antes de las versiones 1.8.16 y 2.0.0-rc.1, el parche de Flarum para CVE-2023-27577 restring\u00eda las caracter\u00edsticas LESS @import y data-uri() en la configuraci\u00f3n custom_less, pero la misma restricci\u00f3n nunca se aplic\u00f3 a otras configuraciones registradas como variables de configuraci\u00f3n LESS (por ejemplo, theme_primary_color y theme_secondary_color, as\u00ed como cualquier clave registrada a trav\u00e9s de Extend\\Settings::registerLessConfigVar()). Esos valores se interpolan literalmente en el c\u00f3digo fuente LESS en tiempo de compilaci\u00f3n, permitiendo a un administrador autenticado crear un valor de color de tema que inyecta una directiva @import arbitraria en el archivo forum.css compilado. Debido a que el analizador LESS subyacente respeta @import (inline) \u2019[path]\u2019, un atacante puede leer ficheros arbitrarios accesibles por el proceso PHP (inclusi\u00f3n local de ficheros) o desencadenar peticiones HTTP(S) salientes (falsificaci\u00f3n de petici\u00f3n del lado del servidor). Este problema ha sido parcheado en las versiones 1.8.16 y 2.0.0-rc.1."}], "id": "CVE-2026-41887", "lastModified": "2026-10-26T18:10:00.173", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 4.9, "baseSeverity": "MEDIUM", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "HIGH", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N", "version": "3.1"}, "exploitabilityScore": 1.2, "impactScore": 3.6, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-41887", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-05-08T19:26:06.629218Z", "version": "2.0.3"}}]}, "published": "2026-05-08T17:16:30.890", "references": [{"source": "security-advisories@github.com", "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": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/flarum/framework/security/advisories/GHSA-xjvc-pw2r-6878"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-22"}, {"lang": "en", "value": "CWE-918"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

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