Cloudreve up to 4.12.x API Endpoint time.Now.UnixNano weak prng

Summaryinfo

A vulnerability labeled as problematic has been found in Cloudreve up to 4.12.x. This vulnerability affects the function time.Now.UnixNano of the component API Endpoint. Executing a manipulation can lead to weak prng. The identification of this vulnerability is CVE-2026-25726. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic was found in Cloudreve up to 4.12.x. This vulnerability affects the function time.Now.UnixNano of the component API Endpoint. The manipulation with an unknown input leads to a weak prng vulnerability. The CWE definition for the vulnerability is CWE-338. The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong. As an impact it is known to affect confidentiality. CVE summarizes:

Cloudreve is a self-hosted file management and sharing system. Prior to version 4.13.0, the application uses the weak pseudo-random number generator math/rand seeded with time.Now().UnixNano() to generate critical security secrets, including the secret_key, and hash_id_salt. These secrets are generated upon first startup and persisted in the database. An attacker can exploit this by obtaining the administrator's account creation time (via public API endpoints) to narrow the search window for the PRNG seed, and use known hashid to validate the seed. By brute-forcing the seed (demonstrated to take <3 hours on general consumer PC), an attacker can predict the secret_key. This allows them to forge valid JSON Web Tokens (JWTs) for any user, including administrators, leading to full account takeover and privilege escalation. This issue has been patched in version 4.13.0.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-25726 since 02/05/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1600.001.

Upgrading to version 4.13.0 eliminates this vulnerability. The upgrade is hosted for download at github.com.

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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

Website

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

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