CVE-2021-21274

Description

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.

Risk Information

Base Score

6.5

MODERATE

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

EPSS Score

Exploitation Probability

0.581

Associated Vulnerability

Vulnerability	OS Platform
Vulnerabilities CVE-2021-21273,CVE-2021-21274 are fixed in Python-matrix-synapse 1.25.0	Windows
Vulnerabilities CVE-2021-21273,CVE-2021-21274 are fixed in Python-matrix-synapse for linux 1.25.0	Linux

Patch Details

No records found

References

https://nvd.nist.gov/vuln/detail/CVE-2023-1234
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-1234