| Bug ID | 1182895 |
|---|---|
| Summary | VUL-0: CVE-2021-21274: matrix-synapse: malicious homeserver could redirect requests to their .well-known file to a large file |
| Classification | openSUSE |
| Product | openSUSE Distribution |
| Version | Leap 15.2 |
| Hardware | Other |
| URL | https://smash.suse.de/issue/278710/ |
| OS | Other |
| Status | NEW |
| Severity | Minor |
| Priority | P5 - None |
| Component | Basesystem |
| Assignee | okurz@suse.com |
| Reporter | abergmann@suse.com |
| QA Contact | security-team@suse.de |
| Found By | Security Response Team |
| Blocker | --- |
CVE-2021-21274 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. References: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-21274 https://github.com/matrix-org/synapse/releases/tag/v1.25.0 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21274 https://github.com/matrix-org/synapse/commit/ff5c4da1289cb5e097902b3e55b771be342c29d6 https://github.com/matrix-org/synapse/pull/8950 https://github.com/matrix-org/synapse/security/advisories/GHSA-2hwx-mjrm-v3g8