CVE-2021-41178: File Traversal affecting SVG files on Nextcloud Server
Nextcloud is an open-source, self-hosted productivity platform. Prior to versions 20.0.13, 21.0.5, and 22.2.0, a file traversal vulnerability makes an attacker able to download arbitrary SVG images from the host system, including user provided files. This could also be leveraged into a XSS/phishing attack, an attacker could upload a malicious SVG file that mimics the Nextcloud login form and send a specially crafted link to victims. The XSS risk here is mitigated due to the fact that Nextcloud employs a strict Content-Security-Policy disallowing execution of arbitrary JavaScript. It is recommended that the Nextcloud Server be upgraded to 20.0.13, 21.0.5 or 22.2.0. There are no known workarounds aside from upgrading.
Affected Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is CVE-2021-41178?
CVE-2021-41178 is a file traversal vulnerability in Nextcloud versions 20.0.3 to 20.0.13, 21.0.1 to 21.0.5, and 22.1.1 to 22.2.0 that allows an attacker to download arbitrary SVG images from the host system.
How can an attacker exploit CVE-2021-41178?
An attacker can exploit CVE-2021-41178 by leveraging the file traversal vulnerability to download arbitrary SVG images, which could also be used for XSS/phishing attacks.
What is the severity of CVE-2021-41178?
CVE-2021-41178 has a severity score of 6.5 (high).
What software versions are affected by CVE-2021-41178?
Nextcloud versions 20.0.3 to 20.0.13, 21.0.1 to 21.0.5, and 22.1.1 to 22.2.0 are affected by CVE-2021-41178.
How can I fix CVE-2021-41178?
To fix CVE-2021-41178, upgrade to Nextcloud versions 20.0.14, 21.0.6, or 22.2.1 or later.