CVE Vulnerability

CVE-2023-22487

Flarum is a forum software for building communities. Using the mentions feature provided by the flarum/mentions extension, users can mention any post ID on the forum with the special `@""#p` syntax. The following behavior never changes no matter if the actor should be able to read the mentioned post or not: A URL to the mentioned post is inserted into the actor post HTML, leaking its discussion ID and post number. The `mentionsPosts` relationship included in the `POST /api/posts` and `PATCH /api/posts/` JSON responses leaks the full JSON:API payload of all mentioned posts without any access control. This includes the content, date, number and attributes added by other extensions. An attacker only needs the ability to create new posts on the forum to exploit the vulnerability. This works even if new posts require approval. If they have the ability to edit posts, the attack can be performed even more discreetly by using a single post to scan any size of database and hiding the attack post content afterward. The attack allows the leaking of all posts in the forum database, including posts awaiting approval, posts in tags the user has no access to, and private discussions created by other extensions like FriendsOfFlarum Byobu. This also includes non-comment posts like tag changes or renaming events. The discussion payload is not leaked but using the mention HTML payload it's possible to extract the discussion ID of all posts and combine all posts back together into their original discussions even if the discussion title remains unknown. All Flarum versions prior to 1.6.3 are affected. The vulnerability has been fixed and published as flarum/core v1.6.3. As a workaround, user can disable the mentions extension.

4.3 /10

CVSS v3.0 : MEDIUM

V3 Legend

Vector :

Exploitability : 2.8 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References
Link Resource
https://github.com/flarum/framework/commit/ab1c868b978e8b0d09a5d682c54665dae17d0985 Patch Third Party Advisory
https://github.com/flarum/framework/security/advisories/GHSA-22m9-m3ww-53h3 Exploit Mitigation
Configurations

Configuration 1

cpe:2.3:a:flarum:flarum:*:*:*:*:*:*:*:*
Information

Published : 2023-01-11 08:15

Updated : 2023-01-19 04:26

NVD link : CVE-2023-22487

Mitre link : CVE-2023-22487

Products Affected
No products.
CWE
NVD-CWE-noinfo