#VU53829 Improper Handling of Unexpected Data Type in Nextcloud Server - CVE-2021-32655

Vulnerability identifier: #VU53829

Vulnerability risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-32655

CWE-ID: CWE-241

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 compromise the target system.

The vulnerability exists due to the files drop public link can be added as federated share. A remote attacker can convert a files drop link to a federated share, leading to an issue on the UI side of the sharing user.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 19.0.0 - 21.0.1

---

External links
https://hackerone.com/reports/1167929
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-grph-cm44-p3jv

---

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.