Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Matrix | Synapse | < 1.47.1 |
| Fedoraproject | Fedora | 34 |
Related Weaknesses (CWE)
References
- https://github.com/matrix-org/synapse/commit/91f2bd090PatchThird Party Advisory
- https://github.com/matrix-org/synapse/releases/tag/v1.47.1Release NotesThird Party Advisory
- https://github.com/matrix-org/synapse/security/advisories/GHSA-3hfw-x7gx-437cMitigationThird Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro
- https://github.com/matrix-org/synapse/commit/91f2bd090PatchThird Party Advisory
- https://github.com/matrix-org/synapse/releases/tag/v1.47.1Release NotesThird Party Advisory
- https://github.com/matrix-org/synapse/security/advisories/GHSA-3hfw-x7gx-437cMitigationThird Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro
FAQ
What is CVE-2021-41281?
CVE-2021-41281 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 remo...
How severe is CVE-2021-41281?
CVE-2021-41281 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2021-41281?
Check the references section above for vendor advisories and patch information. Affected products include: Matrix Synapse, Fedoraproject Fedora.