CVE-2021-21274

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Source
https://cve.org/CVERecord?id=CVE-2021-21274
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-21274.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2021-21274
Aliases
Downstream
Related
Published
2021-02-26T18:15:12.237Z
Modified
2026-04-11T12:35:24.483249Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H CVSS Calculator
Summary
[none]
Details

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.

Database specific 
{
    "unresolved_ranges": [
        {
            "cpe": "cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*",
            "source": "CPE_FIELD",
            "extracted_events": [
                {
                    "last_affected": "34"
                }
            ]
        }
    ]
}
References

Affected packages

Git / github.com/matrix-org/synapse

Affected ranges

Type
GIT
Repo
https://github.com/matrix-org/synapse
Events
Introduced
3bd9daf4b86ed811c9ced95a4adb9aa58b681399
Fixed
ebd534b58d9d53dc5086a9dd9cb176868c7b93ef
Fixed
ff5c4da1289cb5e097902b3e55b771be342c29d6
Database specific 
{
    "cpe": "cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*",
    "source": [
        "CPE_FIELD",
        "REFERENCES"
    ],
    "extracted_events": [
        {
            "introduced": "0.99.0"
        },
        {
            "fixed": "1.25.0"
        }
    ]
}

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-21274.json"