CVE-2026-67204 (GCVE-0-2026-67204)
Vulnerability from cvelistv5 – Published: 2026-08-24 15:33 – Updated: 2026-08-29 11:47 X_Open Source
VLAI
EPSS
VEX
Title
BookStack < 26.05.4 Broken Access Control via Image Gallery API
Summary
BookStack before 26.05.4 contains a broken access control vulnerability that allows authenticated API users with image-update or image-delete permissions to manipulate other users' avatars by exploiting missing content-type restrictions in the Image Gallery API endpoints. Attackers can supply a user avatar's ID to the API controller, which loads any image type without the web controller's gallery and drawio restrictions, and when the avatar's uploaded_to field matches a page ID accessible to the attacker, the authorization check passes allowing the attacker to rename, replace, or delete the target user's avatar without requiring user-management permission.
Severity
5.4 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-24 17:20 UTC
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://www.bookstackapp.com/blog/bookstack-relea… | vendor-advisory |
| https://codeberg.org/bookstack/bookstack/releases… | release-notes |
| https://github.com/BookStackApp/BookStack/release… | release-notes |
| https://www.vulncheck.com/advisories/bookstack-br… | third-party-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| BookStackApp | BookStack |
Affected:
0 , < 26.05.4
(custom)
|
guessed |
Date Public
2026-08-24 00:00
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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