CVE-2021-21402 Unauthenticated Arbitrary File Access in Jellyfin

High 7.7 Published 23 Mar 2021 Updated 3 Aug 2024

Unauthenticated attackers can read arbitrary files from the Jellyfin server filesystem via crafted requests, exposing sensitive data.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2021-21402?

CVE-2021-21402 is a high-severity path traversal vulnerability in jellyfin, published on 23 Mar 2021. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Jellyfin is a Free Software Media System. In Jellyfin before version 10.7.1, with certain endpoints, well crafted requests will allow arbitrary file read from a Jellyfin server's file system. This issue is more prevalent when Windows is used as the host OS. Servers that are exposed to the public Internet are potentially at risk. This is fixed in version 10.7.1. As a workaround, users may be able to restrict some access by enforcing strict security permissions on their filesystem, however, it is recommended to update as soon as possible.

Weakness: CWE-22

Which versions are affected by CVE-2021-21402?

It affects 1 product.

Products include Jellyfin Jellyfin.

How do I fix CVE-2021-21402?

No fix has been published for CVE-2021-21402 yet. Limit exposure of the affected software until one is available.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2021-21402 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-21402 exists.

Public exploit code: 1 Nuclei template and 3 proofs of concept on GitHub.

Sources

Also known as GHSA-wg4c-c9g9-rxhx.