CVE-2021-32802 Preview generation used third-party library not suited for user-generated content in Nextcloud server
Nextcloud server allows attackers to trigger SSRF, file disclosure, or code execution via unsafe third-party library usage during image preview generation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-32802?
CVE-2021-32802 is a critical server-side request forgery vulnerability in Nextcloud Nextcloud Server, published on 7 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Nextcloud server is an open source, self hosted personal cloud. Nextcloud supports rendering image previews for user provided file content. For some image types, the Nextcloud server was invoking a third-party library that wasn't suited for untrusted user-supplied content. There are several security concerns with passing user-generated content to this library, such as Server-Side-Request-Forgery, file disclosure or potentially executing code on the system. The risk depends on your system configuration and the installed library version. It is recommended that the Nextcloud Server is upgraded to 20.0.12, 21.0.4 or 22.1.0. These versions do not use this library anymore. As a workaround users may disable previews by setting `enable_previews` to `false` in `config.php`.
Weakness: CWE-829
Which versions are affected by CVE-2021-32802?
It affects 1 product.
Products include Nextcloud Nextcloud Server.
How do I fix CVE-2021-32802?
Upgrade to a fixed version.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2021-32802 being exploited?
There is no known exploitation of CVE-2021-32802 in the wild and no public exploit code.
Other vulnerabilities in Nextcloud Nextcloud Server
- CVE-2023-26482 Scope of workflow operations is not validated in nextcloud server
- CVE-2018-3775 Auth bypass in Nextcloud Server
- CVE-2023-35172 Nextcloud Server password reset endpoint is not brute force protected
- CVE-2023-32320 Nextcloud Server's brute force protection allows someone to send more requests than intended
- CVE-2021-32656 Trusted servers exchange can be triggered by attacker
Sources
Also known as GHSA-m682-v4g9-wrq7.