Cloudreve: Storage-quota TOCTOU race allows quota bypass and storage-based denial of service

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-77633
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-22 16:17:55 UTC
Updated2026-09-26 00:16:35 UTC
DescriptionCloudreve 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.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

EPSS: 0.003680000 probability, percentile 0.281530000 (date 2026-09-27)

Problem Types: CWE-362 | CWE-367 | CWE-770 | CWE-362 CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') | CWE-367 CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition | CWE-770 CWE-770: Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
3.1CNADECLARED7.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Cloudreve Cloudreve affected < 4.18.0 Not specified

References

ReferenceSourceLinkTags
github.com/cloudreve/cloudreve/security/advisories/GHSA-xj3h-wwxq-gfcj [email protected] github.com
github.com/cloudreve/cloudreve/commit/7329602751c00bb4136fe9ad8b364d0df7... [email protected] github.com
github.com/cloudreve/cloudreve/releases/tag/4.18.0 [email protected] github.com
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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