Cloudreve: Storage-quota TOCTOU race allows quota bypass and storage-based denial of service (CVE-2026-77633) | HOL Guard CVE

High · CVSS 7.1CVE-2026-77633

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

Answer in brief

CVE-2026-77633 records a High severity (CVSS 7.1) vulnerability in Cloudreve: Storage-quota TOCTOU race allows quota bypass and storage-based denial of service. The current sources do not mark it as known exploited. The current feed maps cloudreve/cloudreve (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 22, 2026Updated Sep 22, 2026Source checked Sep 22, 2026First seen by HOL Sep 22, 2026Material review Sep 22, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.1
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 7.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps cloudreve/cloudreve (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
cloudreve/cloudrevegeneric	<4.18.0	4.18.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for cloudreve/cloudreve.
Review the reported fix. Update cloudreve/cloudreve to 4.18.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 22, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.