OpenSSL CVE-2026-25726

Cloudreve instances first deployed with versions prior to V4.10.0. Attacker obtains administrator account creation time via public API endpoints to narrow PRNG seed search window, then derives weak security secrets (secret_key, hash_id_salt) to compromise authentication. Remote unauthenticated exploitation.

This vulnerability presents elevated risk despite high attack complexity (AC:H in CVSS vector). The attack is network-accessible (AV:N) and requires no authentication (PR:N) or user interaction (UI:N), enabling remote exploitation against any exposed Cloudreve instance. However, successful exploitation demands: (1) obtaining administrator creation timestamps through public API reconnaissance, (2) computational resources for multi-hour brute-forcing, and (3) access to known hashid values for seed validation. No public exploit code exists and CISA KEV does not list this CVE, indicating no confirmed active exploitation. The impact upon successful exploitation is severe-complete authentication bypass granting full administrative access (C:H/I:H/A:H), enabling data theft, modification, and service disruption. Real-world risk is moderate: while technically exploitable, the 3-hour computational requirement and multi-step attack chain reduce likelihood compared to simple remote code execution. Organizations running Cloudreve instances deployed before v4.10.0 should prioritize patching, as the attack complexity decreases over time with more powerful hardware and refined techniques. The persistence of weak secrets across upgrades creates a long-tail vulnerability affecting older deployments even if current versions are installed.

An attacker identifies a publicly accessible Cloudreve instance and queries unauthenticated API endpoints to retrieve the administrator account creation timestamp, narrowing the PRNG seed search space to a specific timeframe. Using publicly observable hashid values from the application, the attacker runs a brute-force script on consumer-grade hardware (demonstrated to complete in under 3 hours) to test candidate seeds generated from timestamps around the creation window until finding one that reproduces the known hashids. With the recovered seed, the attacker regenerates the secret_key, forges a valid JWT for the administrator account, and authenticates to the Cloudreve instance with full administrative privileges, enabling data exfiltration, modification of stored files, creation of backdoor accounts, and complete takeover of the cloud storage system.