CVE-2026-77165Public exploitNetwork attack vectorHinoki check available

Authenticated file modification denial via token locks

Published Sep 21, 2026 · Updated Sep 21, 2026

Improper access control in Nextcloud Server 32.0.0 through 34.0.0 allows remote authenticated users to keep files locked indefinitely. The Files Lock app's LockService::canUnlock method accepted only the WebDAV lock token or lock owner's identity for TYPE_TOKEN locks, omitting the underlying file owner's override. An authenticated user able to place a token-based WebDAV lock on another user's file can deny the owner the ability to modify it until the lock is removed from the database.

CVSS severity6.5
Medium
EPSS probability0.41%
Next 30 days · Oct 18, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Improper access control in Nextcloud Server 32.0.0 through 34.0.0 allows remote authenticated users to keep files locked indefinitely. The Files Lock app's LockService::canUnlock method accepted only the WebDAV lock token or lock owner's identity for TYPE_TOKEN locks, omitting the underlying file owner's override. An authenticated user able to place a token-based WebDAV lock on another user's file can deny the owner the ability to modify it until the lock is removed from the database.

The record

CVE
CVE-2026-77165
Published
Sep 21, 2026
Updated
Sep 21, 2026
Vendor
Nextcloud GmbH
Product
Nextcloud Server
Classifications
CWE-284
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 21, 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=32.0.0 <=34.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Serverversion=32.0.0 <=34.0.0

Published CVSS scores

6.5HackerOneCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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.

Activity data is delayed. The latest report is Sep 28, 2026.

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No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control

Public exploit references

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Technologies

Your stack

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