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CVE-2026-84695 Details

ANALYZED

This CVE record has been analyzed and enriched by NVDAPI.com as an independent party.

Description

BookStack before 26.05.4 contains a stored cross-site scripting vulnerability in the drawing upload endpoint that accepts unvalidated base64 content and stores it without content inspection. Attackers with editor permissions can upload SVG files containing scripts that execute in administrator browsers when accessed through the image gallery API without content-type validation or CSP headers.

Metrics

CVSS 3.x Severity and Vector Strings:

VolerionCVSS-B:7.7 HIGHVector:CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

CNA: [email protected]CVSS-B:8.7 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://github.com/BookStackApp/BookStack	[email protected]	Vendor
https://github.com/BookStackApp/BookStack/blob/v26.05.3/app/Uploads/ImageService.php	[email protected]	Source CodeVendor
https://github.com/BookStackApp/BookStack/commit/ac0348a79f3ddd004ca87703948cb9c7d19a420a	[email protected]	Source CodeVendor
https://github.com/BookStackApp/BookStack/releases/tag/v26.05.4	[email protected]	Release NotesVendor
https://www.bookstackapp.com/blog/bookstack-release-v26-05-4/	[email protected]	Release NotesVendor
https://www.vulncheck.com/advisories/bookstack-before-26.05.4-stored-xss-via-drawing-upload	[email protected]	AdvisoryRemedy

see all 6 references

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-79	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')	[email protected]

Affected Products

Product	Versions
BookStack	>= 0, < 26.05.4
CPE cpe:2.3:a:bookstackapp:bookstack:::::::: Remediation Upgrade: 26.05.4moderate efforthttps://github.com/BookStackApp/BookStack/releases/tag/v26.05.4 Mitigation:low effort Verify that the image upload folders do not contain unexpected non-image content. On a typical Linux-based system installation, this can be done using the following commands: # Check the general "public" server space find ./public/uploads -type f ! ( -iname ".jpg" -o -iname ".jpeg" -o -iname ".png" -o -iname ".gif" -o -iname ".webp" -o -iname ".avif" -o -iname ".gitignore" -o -iname ".htaccess" ) # Check the internal image storage space find ./storage/uploads/images -type f ! ( -iname ".jpg" -o -iname ".jpeg" -o -iname ".png" -o -iname ".gif" -o -iname ".webp" -o -iname ".avif" -o -iname ".gitignore" -o -iname ".htaccess" )

Product

Versions

BookStack

>= 0, < 26.05.4

CPE

cpe:2.3:a:bookstackapp:bookstack:*:*:*:*:*:*:*:*

Remediation

Upgrade: 26.05.4moderate efforthttps://github.com/BookStackApp/BookStack/releases/tag/v26.05.4
Mitigation:low effort
Verify that the image upload folders do not contain unexpected non-image content. On a typical Linux-based system installation, this can be done using the following commands: # Check the general "public" server space find ./public/uploads -type f ! ( -iname "*.jpg" -o -iname "*.jpeg" -o -iname "*.png" -o -iname "*.gif" -o -iname "*.webp" -o -iname "*.avif" -o -iname ".gitignore" -o -iname ".htaccess" ) # Check the internal image storage space find ./storage/uploads/images -type f ! ( -iname "*.jpg" -o -iname "*.jpeg" -o -iname "*.png" -o -iname "*.gif" -o -iname "*.webp" -o -iname "*.avif" -o -iname ".gitignore" -o -iname ".htaccess" )

Change History

2 change records found show changes

Date	Action	Recorded By
Sep 2, 2026	CVE Modified	CISA-ADP
Sep 2, 2026	New CVE Received	[email protected]