6.5
CVSSv3

CVE-2021-21274

Published: 26/02/2021 Updated: 07/11/2023
CVSS v2 Base Score: 4.3 | Impact Score: 2.9 | Exploitability Score: 8.6
CVSS v3 Base Score: 6.5 | Impact Score: 3.6 | Exploitability Score: 2.8
VMScore: 383
Vector: AV:N/AC:M/Au:N/C:N/I:N/A:P

Vulnerability Summary

Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.25.0, a malicious homeserver could redirect requests to their .well-known file to a large file. This can lead to a denial of service attack where homeservers will consume significantly more resources when requesting the .well-known file of a malicious homeserver. This affects any server which accepts federation requests from untrusted servers. Issue is resolved in version 1.25.0. As a workaround the `federation_domain_whitelist` setting can be used to restrict the homeservers communicated with over federation.

Vulnerability Trend

Vulnerable Product Search on Vulmon Subscribe to Product

matrix synapse

fedoraproject fedora 34