CVE-2026-125870: Auth Bypass (CVSS 4.2)

Description

BookStack before 26.09.3 contains a missing authorization vulnerability in ImageController::checkImagePermission() that allows authenticated non-admin users to bypass page-level content restrictions for images whose owning page has been moved to the recycle bin, because the permission check relies on Page::getPage() which returns null for soft-deleted pages and silently skips the PageView check. Attackers can enumerate sequential image IDs via GET /images/edit/{id} to disclose metadata of restricted images, and users with image-update-all/image-delete-all privileges can rename, replace, or permanently delete images belonging to content they cannot view, persisting the damage even after the page is restored.

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CVSS v3.1 Score

4.2

MEDIUM

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

Weakness Type (CWE)

CWE-863 Incorrect Authorization

References

Other References

https://codeberg.org/bookstack/bookstack/releases/tag/v26.09.3 https://github.com/BookStackApp/BookStack/releases/tag/v26.09.3 https://www.bookstackapp.com/blog/bookstack-release-v26-09-3/ https://www.vulncheck.com/advisories/bookstack-before-broken-access-control-via-imagecontroller

Frequently Asked Questions

What is CVE-2026-125870? +

BookStack before 26.09.3 contains a missing authorization vulnerability in ImageController::checkImagePermission() that allows authenticated non-admin users to bypass page-level content restrictions for images whose owning page has been moved to the recycle bin, because the permission check relies on Page::getPage() which returns null for soft-deleted pages and silently skips the PageView check. Attackers can enumerate sequential image IDs via GET /images/edit/{id} to disclose metadata of restricted images, and users with image-update-all/image-delete-all privileges can rename, replace, or permanently delete images belonging to content they cannot view, persisting the damage even after the page is restored. It has a CVSS v3.1 base score of 4.2 (MEDIUM).

How severe is CVE-2026-125870? +

CVE-2026-125870 has a CVSS v3.1 score of 4.2 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-125870? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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