GHSA-wmg4-8cp2-hpg9

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GHSA-wmg4-8cp2-hpg9

Summary: Sydent vulnerable to denial of service attack via memory exhaustion

Details: ### Impact Sydent does not limit the size of requests it receives from HTTP clients. A malicious user could send an HTTP request with a very large body, leading to disk space exhaustion and denial of service. Sydent also does not limit response size for requests it makes to remote Matrix homeservers. A malicious homeserver could return a very large response, again leading to memory exhaustion and denial of service. This affects any server which accepts registration requests from untrusted clients. ### Patches Patched by 89071a1, 0523511, f56eee3. ### Workarounds Request sizes can be limited in an HTTP reverse-proxy. There are no known workarounds for the problem with overlarge responses. ### For more information If you have any questions or comments about this advisory, email us at [email protected].

References: https://github.com/matrix-org/sydent/security/advisories/GHSA-wmg4-8cp2-hpg9, https://nvd.nist.gov/vuln/detail/CVE-2021-29430, https://github.com/matrix-org/sydent/commit/0523511d2fb40f2738f8a8549868f44b96e5dab7, https://github.com/matrix-org/sydent/commit/89071a1a754c69a50deac89e6bb74002d4cda19d, https://github.com/matrix-org/sydent/commit/f56eee315b6c44fdd9f6aa785cc2ec744a594428, https://github.com/matrix-org/sydent, https://github.com/matrix-org/sydent/releases/tag/v2.3.0, https://github.com/pypa/advisory-database/tree/main/vulns/matrix-sydent/PYSEC-2021-21.yaml, https://pypi.org/project/matrix-sydent