CVE-2026-62323Public exploitNetwork attack vector

Unauthorized file writes via unenforced WOPI tokens

Published Jul 31, 2026 · Updated Jul 31, 2026

Incorrect authorization in Cloudreve before 4.17.0 allows remote attackers controlling a WOPI viewer to write user files via view sessions. ViewerSessionValidation loads a session by the access token's ID prefix without comparing its random suffix, while WOPI write routes ignore the requested viewer action. Exploitation requires a configured WOPI viewer and a view URL or session ID; writes remain limited to files that the session user can modify.

CVSS severity6.3
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Cloudreve before 4.17.0 allows remote attackers controlling a WOPI viewer to write user files via view sessions. ViewerSessionValidation loads a session by the access token's ID prefix without comparing its random suffix, while WOPI write routes ignore the requested viewer action. Exploitation requires a configured WOPI viewer and a view URL or session ID; writes remain limited to files that the session user can modify.

The record

CVE
CVE-2026-62323
Published
Jul 31, 2026
Updated
Jul 31, 2026
Vendor
Cloudreve
Product
Cloudreve
Classifications
CWE-863, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 31, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 31, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.17.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Cloudreve · Cloudreveversion=< 4.17.0

Published CVSS scores

6.3GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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