CVE-2023-25821 Nextcloud download permissions can be changed by resharer

Medium 5.7 Published 24 Feb 2023 Updated 10 Mar 2025

Attackers can bypass secure view restrictions on internal shares by exploiting reshare permissions, allowing unauthorized data access.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2023-25821?

CVE-2023-25821 is a medium-severity missing authorization vulnerability in Nextcloud Nextcloud Server, published on 24 Feb 2023. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

Nextcloud is an Open Source private cloud software. Versions 24.0.4 and above, prior to 24.0.7, and 25.0.0 and above, prior to 25.0.1, contain Improper Access Control. Secure view for internal shares can be circumvented if reshare permissions are also given. This issue is patched in versions 24.0.7 and 25.0.1. No workaround is available.

Weakness: CWE-284

Which versions are affected by CVE-2023-25821?

It affects 1 product.

Products include Nextcloud Nextcloud Server.

How do I fix CVE-2023-25821?

No fix has been published for CVE-2023-25821 yet. Limit exposure of the affected software until one is available.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2023-25821 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-25821 exists.

All Nextcloud Nextcloud Server vulnerabilities

Sources

Also known as GHSA-7w6h-5qgw-4j94.