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CVE-2021-41281GHSA-3HFW-X7GX-437CPYSEC-2021-436

Path traversal in Matrix Synapse

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 1.47.1
None on Exploit-DB, Metasploit or GitHub

Summary

Synapse is a package for Matrix homeservers written in Python 3/Twisted. Prior to version 1.47.1, Synapse instances with the media repository enabled can be tricked into downloading a file from a remote server into an arbitrary directory. No authentication is required for the affected endpoint. The last 2 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 with a federation whitelist are also unaffected, since Synapse will check the remote hostname, including the trailing `../`s, against the whitelist. Server administrators should upgrade to 1.47.1 or later. Server administrators using a reverse proxy could, at the expense of losing media functionality, may block the certain endpoints as a workaround. Alternatively, non-containerized deployments can be adapted to use the hardened systemd config.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • matrix-org synapse

    fixed in 1.47.1

  • matrix-synapsePyPI

    fixed in 1.47.1

References 5

GitHub · matrix-org/synapse

lists.fedoraproject.org