BookStack before 26.09.3 contains an incorrect authorization vulnerability that allows authenticated users to access
Source GCVE Database
Not known to be exploited · CVSS 5.3 Medium : upgrade to 26.09.3 when convenient.
Data as of 11 Nov 2026, 22:21 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 5.3 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 5.4 |
- Patch
- Available – fixed in 26.09.3
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 11 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.
What to do
Upgrade BookStack to 26.09.3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| BookStackAppBookStack | Affected
| Fixed in
|
GitHubBookStackpkg:github/BookStackOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available in BookStack version 26.09.3. Users should upgrade to this version or later to resolve the incorrect authorization vulnerability. No other mitigation steps are indicated.
Description
BookStack versions prior to 26.09.3 have an authorization vulnerability that allows authenticated users to access or manipulate other users' unpublished draft page images. The flaw arises because the system only checks PageView permission without verifying draft status, enabling attackers to read or tamper with draft images via sequential IDs.
References
- nvd.nist.gov/vuln/detail/CVE-2026-126811 (opens in a new tab)
- github.com/BookStackApp/BookStack/commit/926e16a23f346be47d44746d14cba40cb355cbe1 (opens in a new tab)
- codeberg.org/bookstack/bookstack/commit/4fec06236cbfb314fd72c1b3614c7c50162fb41c (opens in a new tab)
- codeberg.org/bookstack/bookstack/commit/926e16a23f346be47d44746d14cba40cb355cbe1 (opens in a new tab)
- codeberg.org/bookstack/bookstack/releases/tag/v26.09.3 (opens in a new tab)
- github.com/BookStackApp/BookStack/blob/v26.09.2/app/Uploads/Controllers/DrawioImageController.php (opens in a new tab)
- github.com/BookStackApp/BookStack/blob/v26.09.2/app/Uploads/Controllers/ImageController.php (opens in a new tab)
- github.com/BookStackApp/BookStack/releases/tag/v26.09.3 (opens in a new tab)
- github.com/fishtankyu/bookstack-draft-image-idor-advisory.md (opens in a new tab)
- bookstackapp.com/blog/bookstack-release-v26-09-3 (opens in a new tab)
- vulncheck.com/advisories/bookstack-before-26.09.3-incorrect-authorization-via-image-and-drawio-endpoints (opens in a new tab)