CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:M/Au:N/C:N/I:P/A:N
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS
Percentile
50.2%
Synapse instances 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.
Server administrators should upgrade to 1.47.1 or later.
Server administrators using a reverse proxy could, at the expense of losing media functionality, block the following endpoints:
/_matrix/media/r0/download/{serverName}/{mediaId}
/_matrix/media/r0/download/{serverName}/{mediaId}/{fileName}
/_matrix/media/r0/thumbnail/{serverName}/{mediaId}
Alternatively, non-containerized deployments can be adapted to use the hardened systemd config, located at contrib/systemd/override-hardened.conf
.
n/a
If you have any questions or comments about this advisory, e-mail us at [email protected].
github.com/advisories/GHSA-3hfw-x7gx-437c
github.com/matrix-org/synapse/commit/91f2bd090
github.com/matrix-org/synapse/releases/tag/v1.47.1
github.com/matrix-org/synapse/security/advisories/GHSA-3hfw-x7gx-437c
github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2021-436.yaml
lists.fedoraproject.org/archives/list/[email protected]/message/EU7QRE55U4IUEDLKT5IYPWL3UXMELFAS
lists.fedoraproject.org/archives/list/[email protected]/message/N3WY56LCEZ4ZECLWV5KMAXF2PSMUB4F2
nvd.nist.gov/vuln/detail/CVE-2021-41281
CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:M/Au:N/C:N/I:P/A:N
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS
Percentile
50.2%