CVE-2021-41281 log

Severity Medium
Remote Yes
Type Directory traversal
Synapse instances before version 1.47.1 with the media repository enabled can be tricked into downloading a file from a remote server into an arbitrary directory, potentially outside the media store directory.

The last two directories and file name of the path are chosen randomly by Synapse and cannot be controlled by an attacker, which limits the impact.

Homeservers with the media repository disabled are unaffected. Homeservers configured with a federation whitelist are also unaffected.
Group Package Affected Fixed Severity Status Ticket
AVG-2581 matrix-synapse 1.47.0-1 1.47.1-1 Medium Fixed

Server administrators using a reverse proxy could, at the expense of losing media functionality, block the following endpoints:


Alternatively, non-containerized deployments can be adapted to use the hardened systemd config, which is enabled by default for the Arch Linux package.