GHSA-2hwx-mjrm-v3g8MediumCVSS 4.3
Denial of service attack via .well-known lookups
🔗 CVE IDs covered (1)
📋 Description
Impact
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.
Patches
Issue is resolved by #8950. A bug not affecting the security aspects of this was fixed in #9108.
Workarounds
The federation_domain_whitelist setting can be used to restrict the homeservers communicated with over federation.
🎯 Affected products1
- pip/matrix-synapse:>= 0.99.0, < 1.25.0
🔗 References (8)
- https://github.com/matrix-org/synapse/security/advisories/GHSA-2hwx-mjrm-v3g8
- https://nvd.nist.gov/vuln/detail/CVE-2021-21274
- https://github.com/matrix-org/synapse/pull/8950
- https://github.com/matrix-org/synapse/commit/ff5c4da1289cb5e097902b3e55b771be342c29d6
- https://github.com/matrix-org/synapse/releases/tag/v1.25.0
- https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2021-132.yaml
- https://lists.fedoraproject.org/archives/list/[email protected]/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY
- https://github.com/advisories/GHSA-2hwx-mjrm-v3g8