Auth bypass in Nextcloud Files Lock
CVE-2026-82980
Any authenticated user can lock or unlock files they do not own by targeting absolute WebDAV paths of other users. The DAV plugin resolves files from the absolute request URI without verifying that the path segment matches the authenticated session user. This enables: Cross-user manual locks : attacker locks a victim's files, blocking writes (PUT/MOVE/DELETE, editor saves). Lock-token disclosure: the app returns the lock token to unauthorized callers, enabling them to remove token-based locks (client locks) of other users.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.003 (22.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 22.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-82980?
- CVE-2026-82980 is a medium-severity vulnerability in Nextcloud Files Lock, classified under Improper Authentication. CVSS score: 6.3/10. Published 2026-09-18.
- How severe is CVE-2026-82980?
- Medium severity. CVSS v3 base score is 6.3 out of 10.