CVE-2026-45283: Nextcloud: Files Lock app allows users to lock and unlock files of other users

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-01 · updated 2026-07-22
Weakness: CWE-287

Description

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.2, and 33.0.0 to before 33.0.1, the files_lock app did not properly validate the ownership of files when processing DAV lock and unlock requests. An authenticated user could lock or unlock files belonging to other users by targeting their absolute WebDAV paths. Additionally, lock tokens were disclosed to unauthorized callers in error responses, allowing attackers to remove token-based locks placed by other users' client applications. It is recommended that the Nextcloud Server is upgraded to 32.0.2 or 33.0.1. It is recommended that the Nextcloud Enterprise Server is upgraded to 31.0.14.4 or 32.0.2 or 33.0.1

Affected products

Nextcloud Server: from 32.0.0 before 32.0.2; from 33.0.0 before 33.0.1; from 31.0.0 before 31.0.14.4 — fixed in 31.0.14.4, 32.0.2, 33.0.1

How to fix

Upgrade to a fixed version: Nextcloud Server 31.0.14.4, 32.0.2, 33.0.1. Check the vendor advisory for mitigations.

References

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