CVE-2023-48302 Nextcloud Server vulnerable to Self XSS when pasting HTML into Text app with Ctrl+Shift+V

Low 3.5 Published 21 Nov 2023 Updated 2 Aug 2024

Attackers can execute arbitrary scripts in victim browsers by tricking users into pasting HTML into the Text app, potentially leading to account takeover.

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-2023-48302?

CVE-2023-48302 is a low-severity cross-site scripting vulnerability in Nextcloud Nextcloud Server, published on 21 Nov 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 provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.13, 26.0.8, and 27.1.3 of Nextcloud Server and Nextcloud Enterprise Server, when a user is tricked into copy pasting HTML code without markup (Ctrl+Shift+V) the markup will actually render. Nextcloud Server and Nextcloud Enterprise Server versions 25.0.13, 26.0.8, and 27.1.3 contain a fix for this issue. As a workaround, disable app text.

Weakness: CWE-79

Which versions are affected by CVE-2023-48302?

It affects 1 product.

Products include Nextcloud Nextcloud Server.

How do I fix CVE-2023-48302?

No fix has been published for CVE-2023-48302 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2023-48302 being exploited?

There is no known exploitation of CVE-2023-48302 in the wild and no public exploit code.

All Nextcloud Nextcloud Server vulnerabilities

Sources

Also known as GHSA-p7g9-x25m-4h87.