Candidate: CVE-2021-41281
PublicDate: 2021-11-23 20:15:00 UTC
References:
 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-41281
 https://github.com/matrix-org/synapse/security/advisories/GHSA-3hfw-x7gx-437c
 https://github.com/matrix-org/synapse/commit/91f2bd0907f1d05af67166846988e49644eb650c
 https://github.com/matrix-org/synapse/releases/tag/v1.47.1
 https://github.com/matrix-org/synapse/commit/91f2bd090
Description:
 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.
Ubuntu-Description:
Notes:
Mitigation:
Bugs:
Priority: medium
Discovered-by:
Assigned-to:
CVSS:
 nvd: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N [7.5 HIGH]


Patches_matrix-synapse:
upstream_matrix-synapse: released (1.47.1-1)
trusty_matrix-synapse: ignored (out of standard support)
xenial_matrix-synapse: ignored (out of standard support)
bionic_matrix-synapse: needed
focal_matrix-synapse: needed
hirsute_matrix-synapse: ignored (reached end-of-life)
impish_matrix-synapse: needed
jammy_matrix-synapse: needed
devel_matrix-synapse: needed