Nextcloud Files Lock up to 33.0.0 WebDAV Plugin improper authorization

Summaryinfo

A vulnerability, which was classified as critical, was found in Nextcloud Files Lock up to 33.0.0. This affects an unknown part of the component WebDAV Plugin. Executing a manipulation can lead to improper authorization. This vulnerability is tracked as CVE-2026-82980. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability classified as critical was found in Nextcloud Files Lock up to 33.0.0. This vulnerability affects some unknown functionality of the component WebDAV Plugin. The manipulation with an unknown input leads to a improper authorization vulnerability. The CWE definition for the vulnerability is CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at hackerone.com. This vulnerability was named CVE-2026-82980 since 08/31/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/18/2026). The MITRE ATT&CK project declares the attack technique as T1548.002.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-82617). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Cloud Software

Vendor

• Nextcloud

Name

• Files Lock

Version

• 33.0

License

• open-source

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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Once again VulDB remains the best source for vulnerability data.

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