要点
- CVE-2021-21274 は matrix-synapse, synapse (matrix) に影響する深刻度「中」 (CVSS 6.5) の脆弱性です。
- 今後30日間に悪用される確率(EPSS):2.2%(全脆弱性の 82.2% より高い)。
- 対処:1.25.0 以降に更新してください。
概要
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.
NVD の説明
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.
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