CVE-2026-77633

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.

Overview

State: PUBLISHED
Assigner (CNA): GitHub_M
CVSS severity: HIGH
CVSS score: 7.1 / 10
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
Effective score: 7.1 / 10 HIGH source: CNA overview
CWE(s): CWE-362, CWE-367, CWE-770
Reserved: 2026-08-20
Published: 2026-09-22 15:28 UTC
Last updated: 2026-09-22 15:28 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/77xxx/CVE-2026-77633.json
Linked Threat: CVE-2026-77633 — Cloudreve: Storage-quota TOCTOU race allows quota bypass and storage-based denial of service

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-09-22 16:17:55 UTC
NVD last modified: 2026-09-22 16:17:55 UTC
NVD CVSS v3.1: 7.1 / 10 HIGH source: security-advisories@github.com
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
Exploitability subscore: 2.8 / 10
Impact subscore: 4.2 / 10

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-84528
Assigner: GitHub_M
Published: Sep 22, 2026, 3:28:56 PM
Updated: Sep 22, 2026, 3:28:56 PM
EUVD base score (CVSS 3.1): 7.1 / 10
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
EUVD-reported EPSS: 0.0000
Vendors: Cloudreve
Products: Cloudreve (< 4.18.0)
Aliases: GHSA-xj3h-wwxq-gfcj

ENISA 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.

EUVD references (3)

Affected products (1)

Vendor	Product	Versions	Platforms
cloudreve	cloudreve	`< 4.18.0` (affected)	—

Vendor references (3)

References embedded in the original CVE record by the assigning CNA.

https://github.com/cloudreve/cloudreve/security/advisories/GHSA-xj3h-wwxq-gfcj x_refsource_CONFIRM
https://github.com/cloudreve/cloudreve/commit/7329602751c00bb4136fe9ad8b364d0df70773df x_refsource_MISC
https://github.com/cloudreve/cloudreve/releases/tag/4.18.0 x_refsource_MISC

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (3)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://github.com/cloudreve/cloudreve/commit/7329602751c00bb4136fe9ad8b364d0df70773df security-advisories@github.com
https://github.com/cloudreve/cloudreve/releases/tag/4.18.0 security-advisories@github.com
https://github.com/cloudreve/cloudreve/security/advisories/GHSA-xj3h-wwxq-gfcj security-advisories@github.com

Remediations (10)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

CVE-2026-76033 - Vulnerability Details - OpenCVE

web:app.opencve.io

Remediation No vendor fix or workaround currently provided. OpenCVE Recommended Actions Update Chrome to version 151..7922.169 or newer, which contains the fix for the CORS implementation.

2026-09-23 15:15 UTC
Security Update Guide - Microsoft

web:msrc-ppe.microsoft.com

The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.

2026-09-23 15:15 UTC
Security Update Guide - Microsoft Security Response Center

web:msrc.microsoft.com

Security Update Guide - Microsoft Security Response Center

2026-09-23 15:15 UTC
Nvd-cve-2026-76033

web:nvd.nist.gov

NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.

2026-09-23 15:15 UTC
Cisco Advance Notification for Publication of September 16, 2026 ...

web:sec.cloudapps.cisco.com

On September 16, 2026 , the Cisco Product Security Incident Response Team (PSIRT) published the advisories that are listed in the following tables. To remediate these vulnerabilities, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories. For more information about changes in Cisco PSIRT vulnerability disclosure, see Strengthening the ...

2026-09-23 15:15 UTC
Microsoft Patch Tracker (September 2026): Exploit-Ranked | Senserva

web:senserva.com

Every Microsoft security patch (KB) and the CVEs it fixes, with severity, CVSS, and CISA KEV status. Cross-linked to the CVE reference.

2026-09-23 15:15 UTC
July 18, 2026—Hotpatch KB5121768 (OS Builds 26200.8893 and 26100.8893 ...

web:support.microsoft.com

This out-of-band (OOB) update for Windows 11, version 25H2 and Windows 11, version 24H2 (KB5121768) is cumulative. It includes all improvements from previous security and non-security updates, along with an additional fix . Improvements This OOB update includes the following improvement: [System Performance] This update addresses an issue affecting a limited number of devices with an Intel ...

2026-09-23 15:15 UTC
SAP Security Patch Day - June 2026

web:support.sap.com

SAP security Patch Day Bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 9th of June 2026 , SAP security patch day saw the release of 15 new security notes.

2026-09-23 15:15 UTC
DSA-2026-353: Security Update for Cloud Disaster Recovery ...

web:www.dell.com

Cloud Disaster Recovery remediation is available for multiple security vulnerabilities that could be exploited by malicious users to compromise the affected system.

2026-09-23 15:15 UTC
Oracle Critical Patch Update Advisory - July 2026

web:www.oracle.com

This Critical Patch Update contains 1448 new security patches across the product families listed below. Please note that a My Oracle Support (MOS) note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at July 2026 Critical Patch Update: Executive Summary and Analysis.

2026-09-23 15:15 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-77633.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "cloudreve",
          "vendor": "cloudreve",
          "versions": [
            {
              "status": "affected",
              "version": "< 4.18.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-362",
              "description": "CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-367",
              "description": "CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-770",
              "description": "CWE-770: Allocation of Resources Without Limits or Throttling",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-22T15:28:56.700Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/cloudreve/cloudreve/security/advisories/GHSA-xj3h-wwxq-gfcj",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/cloudreve/cloudreve/security/advisories/GHSA-xj3h-wwxq-gfcj"
        },
        {
          "name": "https://github.com/cloudreve/cloudreve/commit/7329602751c00bb4136fe9ad8b364d0df70773df",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/cloudreve/cloudreve/commit/7329602751c00bb4136fe9ad8b364d0df70773df"
        },
        {
          "name": "https://github.com/cloudreve/cloudreve/releases/tag/4.18.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/cloudreve/cloudreve/releases/tag/4.18.0"
        }
      ],
      "source": {
        "advisory": "GHSA-xj3h-wwxq-gfcj",
        "discovery": "UNKNOWN"
      },
      "title": "Cloudreve: Storage-quota TOCTOU race allows quota bypass and storage-based denial of service"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-77633",
    "datePublished": "2026-09-22T15:28:56.700Z",
    "dateReserved": "2026-08-20T20:52:01.927Z",
    "dateUpdated": "2026-09-22T15:28:56.700Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}