Nextcloud Server up to 28.0.9/29.0.6 Background Job weak hash

Summaryinfo

A vulnerability, which was classified as problematic, was found in Nextcloud Server up to 28.0.9/29.0.6. This vulnerability affects unknown code of the component Background Job Handler. Such manipulation leads to weak hash. This vulnerability is traded as CVE-2024-52521. The attack may be launched remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Nextcloud Server up to 28.0.9/29.0.6. It has been rated as problematic. Affected by this issue is some unknown functionality of the component Background Job Handler. The manipulation with an unknown input leads to a weak hash vulnerability. Using CWE to declare the problem leads to CWE-328. The product uses an algorithm that produces a digest (output value) that does not meet security expectations for a hash function that allows an adversary to reasonably determine the original input (preimage attack), find another input that can produce the same hash (2nd preimage attack), or find multiple inputs that evaluate to the same hash (birthday attack). Impacted is integrity. CVE summarizes:

Nextcloud Server is a self hosted personal cloud system. MD5 hashes were used to check background jobs for their uniqueness. This increased the chances of a background job with arguments falsely being identified as already existing and not be queued for execution. By changing the Hash to SHA256 the probability was heavily decreased. It is recommended that the Nextcloud Server is upgraded to 28.0.10, 29.0.7 or 30.0.0.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2024-52521 since 11/11/2024. The exploitation is known to be difficult. The attack may be launched remotely. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1600.001.

Upgrading to version 28.0.10, 29.0.7 or 30.0.0 eliminates this vulnerability. Applying the patch a933ba1fdba77e7d8c6b8ff400e082cf853ea46d is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Cloud Software

Vendor

• Nextcloud

Name

• Server

Version

• 28.0.0
• 28.0.1
• 28.0.2
• 28.0.3
• 28.0.4
• 28.0.5
• 28.0.6
• 28.0.7
• 28.0.8
• 28.0.9
• 29.0.0
• 29.0.1
• 29.0.2
• 29.0.3
• 29.0.4
• 29.0.5
• 29.0.6

License

• open-source

Website

• Product: https://github.com/nextcloud/server/

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