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 1.28.0 Synapse is missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion. Note that the groups feature is not part of the Matrix specification and the chosen maximum lengths are arbitrary. Not all clients might abide by them. Refer to referenced GitHub security advisory for additional details including workarounds.
CVE-2021-21394
Published Date: 2021-04-12T21:15Z
Last Modified: 2023-11-07T03:30Z
CVSS Score: 6.5 (MEDIUM)
EPSS Score: 0.19%
Risk Score: 4.55 (MEDIUM)
Risk Score based on CVSS score and EPSS. This score is for reference purposes and is not internationally recognized.
CVSS:
6.5 |
EPSS:
0.19%
Mitre ATT&CK Technical v15.1
T1153 – Source
T1583.004 – Server
T1059.006 – Python
T1584.004 – Server
T1053.002 – At
Technical Analysis & Mitigation Measures
Reference Links
https://github.com/matrix-org/synapse/pull/9321
https://pypi.org/project/matrix-synapse/
https://github.com/matrix-org/synapse/pull/9393
https://github.com/matrix-org/synapse/security/advisories/GHSA-w9fg-xffh-p362
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/
Vendor - Produce - Version
synapse - matrix, fedora - fedoraproject
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