CVE-2023-28835 Insecure randomness for default password in nextcloud

Low 3.5 Published 30 Mar 2023 Updated 11 Feb 2025

Attackers can brute-force weak default share passwords in Nextcloud if no password policy is enabled, potentially gaining unauthorized access to shared data.

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-2023-28835?

CVE-2023-28835 is a low-severity vulnerability in Nextcloud Nextcloud Server, published on 30 Mar 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 server is an open source home cloud implementation. In affected versions the generated fallback password when creating a share was using a weak complexity random number generator, so when the sharer did not change it the password could be guessable to an attacker willing to brute force it. It is recommended that the Nextcloud Server is upgraded to 24.0.10 or 25.0.4. This issue only affects users who do not have a password policy enabled, so enabling a password policy is an effective mitigation for users unable to upgrade.

Weakness: CWE-338

Which versions are affected by CVE-2023-28835?

It affects 1 product.

Products include Nextcloud Nextcloud Server.

How do I fix CVE-2023-28835?

No fix has been published for CVE-2023-28835 yet. Limit exposure of the affected software until one is available.

Is CVE-2023-28835 being exploited?

There is no known exploitation of CVE-2023-28835 in the wild and no public exploit code.

All Nextcloud Nextcloud Server vulnerabilities

Sources

Also known as GHSA-7w2p-rp9m-9xp9.