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 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.
OS | Version | Architecture | Package | Version | Filename |
---|---|---|---|---|---|
ubuntu | 18.04 | noarch | matrix-synapse | < any | UNKNOWN |
ubuntu | 20.04 | noarch | matrix-synapse | < any | UNKNOWN |
ubuntu | 22.04 | noarch | matrix-synapse | < any | UNKNOWN |
github.com/matrix-org/synapse/commit/91f2bd090
github.com/matrix-org/synapse/commit/91f2bd0907f1d05af67166846988e49644eb650c
github.com/matrix-org/synapse/releases/tag/v1.47.1
github.com/matrix-org/synapse/security/advisories/GHSA-3hfw-x7gx-437c
launchpad.net/bugs/cve/CVE-2021-41281
nvd.nist.gov/vuln/detail/CVE-2021-41281
security-tracker.debian.org/tracker/CVE-2021-41281
www.cve.org/CVERecord?id=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%