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.
History

Wed, 02 Apr 2025 13:00:00 +0000

Type Values Removed Values Added
First Time appeared Flarum
Flarum flarum
CPEs cpe:2.3:a:flarum:flarum:*:*:*:*:*:*:*:*
Vendors & Products Flarum
Flarum flarum

Wed, 12 Mar 2025 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 12 Mar 2025 14:15:00 +0000

Type Values Removed Values Added
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.
Title Flarum Vulnerable to Session Hijacking via Authoritative Subdomain Cookie Overwrite
Weaknesses CWE-74
References
Metrics cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-03-12T15:29:21.831Z

Reserved: 2025-03-06T18:06:54.462Z

Link: CVE-2025-27794

cve-icon Vulnrichment

Updated: 2025-03-12T15:27:06.867Z

cve-icon NVD

Status : Analyzed

Published: 2025-03-12T14:15:17.033

Modified: 2025-04-02T12:33:56.437

Link: CVE-2025-27794

cve-icon Redhat

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