Vulnerability identifier: #VU54669

Vulnerability risk: Medium

CVSSv3.1: 6.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-32726

CWE-ID: CWE-708

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Nextcloud Server
Client/Desktop applications / Messaging software

Vendor: Nextcloud

Description

The vulnerability allows a remote attacker to gain access to sensitive information on the target system.

The vulnerability exists due to the Webauthn tokens are not deleted after a user has been deleted. If a victim reuse an earlier used username, the previous user can gain access to their account.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 19.0.0 - 21.0.2

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External links
http://github.com/nextcloud/security-advisories/security/advisories/GHSA-6qr9-c846-j8mg/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.