Resource exhaustion in Cloudreve
CVE-2026-77633
Cloudreve is a self-hosted file management and sharing system. Prior to 4.18.0, PrepareUpload in pkg/filemanager/fs/dbfs/upload.go checks a stale in-memory user storage value through validateUserCapacity and later applies an unconditional storage charge outside the same quota-enforcing transaction. An authenticated user with Files.Write permission can issue concurrent upload-session requests that read the same capacity snapshot, all pass the MaxStorage check, and reserve their declared sizes through CommitWithStorageDiff. The resulting reservations can exceed the account quota and can be materialized as chunked uploads that exhaust host storage and deny uploads to other users. The default local-storage policy and default User group are affected. This issue is fixed in version 4.18.0.
Vulnerability class: Race Condition
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Cloudreve — versions < 4.18.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-77633?
- CVE-2026-77633 is a high-severity vulnerability in Cloudreve, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 7.1/10. Published 2026-09-22.
- How severe is CVE-2026-77633?
- High severity. CVSS v3 base score is 7.1 out of 10.