Cloudreve up to 4.16.x OAuth Signin signin app_id privileges management

Summaryinfo

A vulnerability identified as problematic has been detected in Cloudreve up to 4.16.x. The affected element is an unknown function of the file /api/v4/admin/policy/oauth/signin of the component OAuth Signin Handler. The manipulation of the argument app_id leads to privileges management. This vulnerability is referenced as CVE-2026-55502. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Cloudreve up to 4.16.x. This issue affects some unknown functionality of the file /api/v4/admin/policy/oauth/signin of the component OAuth Signin Handler. The manipulation of the argument app_id with an unknown input leads to a privileges management vulnerability. Using CWE to declare the problem leads to CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Cloudreve is a self-hosted file management and sharing system. Prior to 4.17.0, POST /api/v4/admin/policy/oauth/signin requires only Admin.Read even though GetOauthRedirectService persists caller-supplied OneDrive secret and app_id values, allowing an OAuth token without Admin.Write to modify storage policy credentials. The route is inside the admin group that requires Admin.Read, but it does not add the local Admin.Write guard used by sibling policy mutation routes. Its handler persists attacker-supplied secret and app_id values into the selected OneDrive storage policy before returning an OAuth URL. This issue is fixed in version 4.17.0.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-55502 since 06/17/2026. The exploitation is known to be easy. The attack may be initiated remotely. The exploitation requires an enhanced level of successful authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

Upgrading to version 4.17.0 eliminates this vulnerability.

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Productinfo

Type

• Cloud Software

Name

• Cloudreve

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10
• 4.11
• 4.12
• 4.13
• 4.14
• 4.15
• 4.16

Website

• Product: https://github.com/cloudreve/cloudreve/

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