Cloudanix VulnDB

GHSA-xjvc-pw2r-6878

Medium · 4.9

Flarum: Path traversal in LESS parser via theme color settings (incomplete fix for CVE-2023-27577)

CVSS

4.9

EPSS

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Published

Apr 22, 2026

CISA due date

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The record

Flarum's patch for [CVE-2023-27577](https://github.com/flarum/framework/security/advisories/GHSA-vhm8-wwrf-3gcw) 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).

Affected packages

Ecosystem Package Introduced Fixed

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