Cloudreve: Storage-quota TOCTOU race allows quota bypass and storage-based denial of service
18Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.1
exploitation probability
—
observed exploitation
nono source reports it
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.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
Affected products
cloudreve · cloudreve