Vulnerability identifier: #VU83345

Vulnerability risk: Low

CVSSv3.1: 5.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-48302

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

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

Vendor: Nextcloud

Description

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data when pasting HTML into Text app with Ctrl+Shift+V. A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in user's browser in context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Nextcloud Server: 25.0.0 - 27.1.2

Nextcloud Enterprise Server: 25.0.0 - 27.1.2

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External links
http://github.com/nextcloud/security-advisories/security/advisories/GHSA-p7g9-x25m-4h87

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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.