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CVE-2026-67204

MediumCVSS 5.3 / 10
Published Aug 24, 2026·Last modified Aug 27, 2026
Affected Components(244)
bookstackapp/bookstack
24.10.2
bookstackapp/bookstack
23.12
bookstackapp/bookstack
21.04.2
1 / 82
Description

BookStack before 26.05.4 contains a broken access control vulnerability that allows authenticated API users with image-update or image-delete permissions to manipulate other users' avatars by exploiting missing content-type restrictions in the Image Gallery API endpoints. Attackers can supply a user avatar's ID to the API controller, which loads any image type without the web controller's gallery and drawio restrictions, and when the avatar's uploaded_to field matches a page ID accessible to the attacker, the authorization check passes allowing the attacker to rename, replace, or delete the target user's avatar without requiring user-management permission.

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Risk Scores
Base Score
5.3

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
1.3

Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.

EPSS
0.41%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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