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.
Published: 2021-02-26
Score: 4.3 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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Advisories
Source ID Title
EUVD EUVD EUVD-2021-0124 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.
Github GHSA Github GHSA GHSA-2hwx-mjrm-v3g8 Denial of service attack via .well-known lookups
History

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Subscriptions

Fedoraproject Fedora
Matrix Synapse
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2024-08-03T18:09:15.070Z

Reserved: 2020-12-22T00:00:00.000Z

Link: CVE-2021-21274

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2021-02-26T18:15:12.237

Modified: 2024-11-21T05:47:54.520

Link: CVE-2021-21274

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

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Weaknesses