CVE
BookStack before 26.09.3 Incorrect Authorization via Image and Drawio Endpoints
- Exploited
- No known exploitation
- Fix
- Fixed in 26.09.3
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 26.09.3.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 8/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
BookStack, a wiki and documentation platform, has an incorrect authorization flaw in its image and draw.io endpoints that lets any logged-in user reach other users' unpublished draft page images over the network. An attacker can read draw.io data or rename, replace, or delete draft images by sequential ID, which exposes or alters unpublished work.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
BookStack before 26.09.3 contains an incorrect authorization vulnerability that allows authenticated users to access other users' unpublished draft page images by checking only PageView permission without draft status. Attackers can read drawio data via the base64 endpoint or rename, replace, or delete draft images by sequential ID to disclose or tamper with unpublished work.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure3/25Reachable over the network · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity5.3/10CVSS 5.3
- No patch0/5No signal
What would change the score
- Would score about 63 if added to CISA KEV
- Would score about 58 if CISA's SSVC rates exploitation active
- Would score about 27 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 26.09.3.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-126811 (BookStack before 26.09.3 Incorrect Authorization via Image and Drawio Endpoints), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-126811 (entry last updated 2026-11-11):
Affected:
- BookStackApp BookStack: fixed in 26.09.3
Fixed versions: 26.09.3.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-126811 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126811 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://codeberg.org/bookstack/bookstack/commit/926e16a23f346be47d44746d14cba40cb355cbe1
- https://codeberg.org/bookstack/bookstack/commit/4fec06236cbfb314fd72c1b3614c7c50162fb41c
- https://github.com/BookStackApp/BookStack/commit/926e16a23f346be47d44746d14cba40cb355cbe1
- https://www.bookstackapp.com/blog/bookstack-release-v26-09-3/
- https://codeberg.org/bookstack/bookstack/releases/tag/v26.09.3
- https://github.com/BookStackApp/BookStack/releases/tag/v26.09.3
- https://github.com/BookStackApp/BookStack/blob/v26.09.2/app/Uploads/Controllers/DrawioImageController.php#L82-L92
- https://github.com/BookStackApp/BookStack/blob/v26.09.2/app/Uploads/Controllers/ImageController.php#L159-L169
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-126811
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126811"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- BookStackApp BookStack
fixed in 26.09.3
Evidence 12
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Link
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 9
- Patch
- Patch
- Patch
- Repository
- Repository
Show all 9 sourcesShow fewer sources
- Repository
- Repository
- Link
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-126811
Is CVE-2026-126811 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-126811?
BookStack: before 26.09.3.Source: cve.now feed data
How do I fix CVE-2026-126811?
Upgrade to a fixed version: 26.09.3.Source: cve.now feed data