Vulnerability · Published Mar 12, 2025 · Assigned by GitHub_M
CVE-2025-27794Flarum Vulnerable to Session Hijacking via Authoritative Subdomain Cookie Overwrite
Medium 6.8
In plain English
A medium-severity injection in framework from flarum. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Flarum is open-source forum software. A session hijacking vulnerability exists in versions prior to 1.8.10 when an attacker-controlled authoritative subdomain under a parent domain (e.g., `subdomain.host.com`) sets cookies scoped to the parent domain (`.host.com`). This allows session token replacement for applications hosted on sibling subdomains (e.g., `community.host.com`) if session tokens aren't rotated post-authentication. Key Constraints are that the attacker must control any subdomain under the parent domain (e.g., `evil.host.com` or `x.y.host.com`), and the parent domain must not be on the Public Suffix List. Due to non-existent session token rotation after authenticating we can theoretically reproduce the vulnerability by using browser dev tools, but due to the browser's security measures this does not seem to be exploitable as described. Version 1.8.10 contains a patch for the issue.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Packagist | flarum/core | 1.8.10 | GHSA-hg9j-64wp-m9px |
| Packagist | flarum/framework | 1.8.10 | GHSA-hg9j-64wp-m9px |
Affected products (as reported)
Weakness: CWE-74 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
References
- https://github.com/flarum/framework/security/advisories/GHSA-hg9j-64wp-m9px x_refsource_CONFIRM
- https://github.com/flarum/framework/commit/a05aaea3ee1e0a8b870935183193cd6052f1d402 x_refsource_MISC
- https://github.com/flarum/framework/releases/tag/v1.8.10 x_refsource_MISC