Is CVE-2026-126811 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-126811 being exploited in the wild.

How severe is CVE-2026-126811?

Medium severity, with a CVSS score of 5.4, published 11 November 2026.

Is there a fix for CVE-2026-126811?

Yes: fixed in 26.09.3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-126811 attacked?

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

Am I affected by CVE-2026-126811?

Check whether you run BookStack at an affected version. 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-2026-126811: BookStack authorization bypass in draft page images

CVE-2026-126811 · Severity: medium · CVSS 5.4 · Published 2026-11-11

BookStack is a documentation and wiki platform used to organize and share information within organizations. Authenticated users can view, download, or delete unpublished draft pages and images belonging to other users by exploiting inadequate permission checks, potentially exposing confidential work or disrupting document workflows.

Technologies: BookStack. Vendors: BookStack.

Quick answers

Is CVE-2026-126811 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-126811 being exploited in the wild.
How severe is CVE-2026-126811?: Medium severity, with a CVSS score of 5.4, published 11 November 2026.
Which products and versions are affected?: BookStack before 26.09.3.
Is there a fix for CVE-2026-126811?: Yes: fixed in 26.09.3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-126811 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-126811?: Check whether you run BookStack at an affected version. 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.

How to fix

Fixed in: 26.09.3

Technical details

BookStack fails to check draft status when validating PageView permissions for image endpoints, allowing authenticated attackers to access other users' unpublished draft images via sequential ID enumeration. Attackers can read DrawIO diagram data via base64-encoded endpoints or perform unauthorized operations (rename, replace, delete) on draft images, compromising confidentiality and integrity of unpublished content.

Affected products

BookStack BookStack before 26.09.3

Timeline

2026-11-11: disclosed

References

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