Post mentions can be used to read any post on the forum without access control

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 `@"<username>"#p<id>` 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/<id>` 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.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

访问控制不恰当

Flarum 访问控制错误漏洞

Flarum是Flarum社区的一套开源的论坛系统。 flarum mention 1.6.3之前版本存在访问控制错误漏洞，该漏洞源于允许泄露论坛数据库中的所有帖子，包括等待批准的帖子、用户无权访问的标签中的帖子，以及由 FriendsOfFlarum Byobu 等其他扩展程序创建的私人讨论。这还包括非评论帖子，如标签更改或重命名事件。

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