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CVE-2026-67204— BookStack < 26.05.4 Broken Access Control via Image Gallery API

Quick assessment

Affected
BookStackApp BookStack
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Bookstackapp BookStack是Bookstackapp团队开源的一款文档管理系统。 Bookstackapp BookStack 26.05.4之前版本存在授权问题漏洞，该漏洞源于Image Gallery API端点缺少内容类型限制，导致访问控制失效，可能允许具有图像更新或删除权限的已认证API用户重命名、替换或删除其他用户的头像，而无需用户管理权限。

CVSS 5.4 · Medium EPSS 0.41% · P35

Affected Version Matrix 1

VendorProduct Version RangeStatus
BookStackApp BookStack < 26.05.4 affected
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I. Basic Information for CVE-2026-67204

Vulnerability Information
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Vulnerability Title
BookStack < 26.05.4 Broken Access Control via Image Gallery API
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制不正确
Source: CVE Program / CVE List V5
Vulnerability Title
Bookstackapp BookStack 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Bookstackapp BookStack是Bookstackapp团队开源的一款文档管理系统。 Bookstackapp BookStack 26.05.4之前版本存在授权问题漏洞，该漏洞源于Image Gallery API端点缺少内容类型限制，导致访问控制失效，可能允许具有图像更新或删除权限的已认证API用户重命名、替换或删除其他用户的头像，而无需用户管理权限。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
BookStackApp BookStack 0 ~ 26.05.4 -

II. Public POCs for CVE-2026-67204

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III. Intelligence Information for CVE-2026-67204

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Vendor Advisories for CVE-2026-67204 (1)

Security Blog Posts for CVE-2026-67204 (1)

Vendor Pages for CVE-2026-67204 (2)

IV. Related Vulnerabilities

Same product: BookStack
Same vendor: BookStackApp
Same weakness: CWE-863

V. Comments for CVE-2026-67204

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