CVE-2021-21274

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Source

https://cve.org/CVERecord?id=CVE-2021-21274

Import Source

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

JSON Data

https://api.osv.dev/v1/vulns/CVE-2021-21274

Aliases

Downstream

Published

2021-02-26T18:15:12Z

Modified

2026-10-20T10:54:27Z

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": [
        {
            "cpes": [
                "cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*"
            ],
            "extracted_events": [
                {
                    "range": [
                        {
                            "introduced": "34"
                        },
                        {
                            "last_affected": "34"
                        }
                    ],
                    "source": "CPE_STRING"
                }
            ],
            "vendor_product": "fedoraproject:fedora"
        }
    ]
}

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

Show details

{
    "extracted_events": [
        {
            "cpe": "cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*",
            "range": [
                {
                    "introduced": "0.99.0"
                },
                {
                    "fixed": "1.25.0"
                }
            ],
            "source": "CPE_RANGE"
        },
        {
            "range": [
                {
                    "fixed": "ff5c4da1289cb5e097902b3e55b771be342c29d6"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "original_tag": "v1.25.0",
            "range": [
                {
                    "fixed": "ebd534b58d9d53dc5086a9dd9cb176868c7b93ef"
                }
            ],
            "source": "REFERENCES_TAG"
        }
    ]
}

Database specific

source

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