CVE-2026-67204

MEDIUMPre-NVD 5.45.4—
EchelonGraph scoreHIGH confidence

Score 5.4 from GitHub Security Advisory published 2026-08-24. the CNA's CVSS baseline 5.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, epss, ghsa
Trending — 4 sources updated this week
5.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.4Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
5.4
EG Score
5.4(high)
EG Risk
24(Track)
EG Risk 24/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity54% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
15%
KEV
Not listed

Published

August 24, 2026

Last Modified

August 29, 2026

Advisory Details (4)

Auto-updated Aug 24, 2026
Patch available. Sources: github_release.
generic

BookStack < 26.05.4 Broken Access Control via Image Gallery API | Advisories | VulnCheck

https://www.vulncheck.com/advisories/bookstack-broken-access-control-via-image-gallery-api
github_release Patch Available

BookStack v26.05.4

Patch available: BookStackApp/BookStack v26.05.4

https://github.com/BookStackApp/BookStack/releases/tag/v26.05.4
generic

Cookie monster!

https://codeberg.org/bookstack/bookstack/releases/tag/v26.05.4
generic

BookStack Security Release v26.05.4 · BookStack

https://www.bookstackapp.com/blog/bookstack-release-v26-05-4/

Vendor Advisories for CVE-2026-67204(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 19× in last 7d / 19× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 12:03 UTCEG score recompute
  3. 2026-08-29 12:03 UTCGHSA enrichment
  4. 2026-08-29 00:27 UTCEG score recompute
  5. 2026-08-29 00:26 UTCGHSA enrichment
  6. 2026-08-28 21:42 UTCEPSS rescore
  7. 2026-08-27 21:03 UTCEG score recompute
  8. 2026-08-27 21:03 UTCGHSA enrichment
  9. 2026-08-26 20:11 UTCEG score recompute
  10. 2026-08-26 20:11 UTCGHSA enrichment
  11. 2026-08-26 14:47 UTCEPSS rescore
  12. 2026-08-25 19:14 UTCEG score recompute
  13. 2026-08-25 19:14 UTCGHSA enrichment
  14. 2026-08-25 13:49 UTCEPSS rescore
  15. 2026-08-24 18:23 UTCEG score recompute
  16. 2026-08-24 17:36 UTCEG score recompute
  17. 2026-08-24 16:25 UTCEG score recompute
  18. 2026-08-24 15:46 UTCEG score recompute
  19. 2026-08-24 15:46 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-67204?
CVE-2026-67204 is a medium vulnerability published on August 24, 2026. 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…
When was CVE-2026-67204 disclosed?
CVE-2026-67204 was first published in the National Vulnerability Database on August 24, 2026, with the most recent update on August 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-67204 actively exploited?
CVE-2026-67204 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 85.4% of all scored CVEs.
What is the CVSS score of CVE-2026-67204?
CVE-2026-67204 has a CVSS v4.0 base score of 5.4 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-67204?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-67204, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-67204

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