Denial of service (via resource exhaustion) due to improper input validation on third-party identifier endpoints
CVE-2021-21394

5.3MEDIUM

Key Information:

Vendor

Matrix-org

Status
Synapse
Vendor
CVE Published:
12 April 2021

What is CVE-2021-21394?

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.

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Affected Version(s)

synapse < 1.28.0

References

https://github.com/matrix-org/synapse/security/advisories...
x_refsource_CONFIRM
https://pypi.org/project/matrix-synapse/
x_refsource_MISC
https://github.com/matrix-org/synapse/pull/9321
x_refsource_MISC

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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