Is CVE-2026-67204 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-67204 being exploited in the wild.

How severe is CVE-2026-67204?

Medium severity, with a CVSS score of 5.4, published 24 August 2026.

Which products and versions are affected?

BookStack BookStack before 26.05.4.

Is there a fix for CVE-2026-67204?

A patch was published on 2026-08-24: Fixed in BookStack v26.05.4 with additional MIME-based content type checks Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-67204 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-67204?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-67204: BookStack broken access control in image API

CVE-2026-67204 · Severity: medium · CVSS 5.4 · Published 2026-08-24

BookStack is a document management and wiki-like platform. The vulnerability allows authenticated users with basic image-management permissions to modify or delete other users' profile pictures (avatars) by exploiting insufficient access controls in the API. An attacker could replace or delete any user's avatar without needing administrative privileges, potentially impacting account identity and user trust.

Quick answers

Is CVE-2026-67204 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-67204 being exploited in the wild.
How severe is CVE-2026-67204?: Medium severity, with a CVSS score of 5.4, published 24 August 2026.
Which products and versions are affected?: BookStack BookStack before 26.05.4.
Is there a fix for CVE-2026-67204?: A patch was published on 2026-08-24: Fixed in BookStack v26.05.4 with additional MIME-based content type checks Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-67204 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-67204?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

This is a broken access control vulnerability (CWE-284) in BookStack's Image Gallery API endpoints. The flaw stems from missing content-type validation and insufficient authorization checks when handling image operations. An authenticated attacker with image-update or image-delete permissions can supply a user avatar's ID to the API controller; the system loads the image without gallery and drawio restrictions that are enforced by the web controller. When the avatar's uploaded_to field matches a page ID accessible to the attacker, the authorization check incorrectly passes, allowing rename, replace, or delete operations on target avatars without requiring user-management permission. The vulnerability requires API authentication but can be exploited by lower-privileged users. BookStack 26.05.4 addresses this with enhanced MIME-based content-type validation.

Affected products

BookStack BookStack before 26.05.4

Timeline

2026-08-24: disclosed
2026-08-24: patched: Fixed in BookStack v26.05.4 with additional MIME-based content type checks

References

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