CVE-2026-77633
Cloudreve: Storage-quota TOCTOU race allows quota bypass and storage-based denial of service
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High7.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H |
| NVDNVD · Deferred | 3.1 | High7.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H |
- EPSS (exploitation in 30 days)
- 0.37% · top 69% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.1.
Weakness
- CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') (opens in a new tab)All about CWE-362 and its CVEs
- CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition (opens in a new tab)All about CWE-367 and its CVEs
- CWE-770: Allocation of Resources Without Limits or Throttling (opens in a new tab)All about CWE-770 and its CVEs
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Gogithub.com/cloudreve/Cloudreve/v4GHSA-xj3h-wwxq-gfcj (opens in a new tab)
References (3)
- https://github.com/cloudreve/cloudreve/security/advisories/GHSA-xj3h-wwxq-gfcj (opens in a new tab)x_refsource_CONFIRM
- https://github.com/cloudreve/cloudreve/commit/7329602751c00bb4136fe9ad8b364d0df70773df (opens in a new tab)x_refsource_MISC
- https://github.com/cloudreve/cloudreve/releases/tag/4.18.0 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-xj3h-wwxq-gfcj (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-77633)Record last updated .