CVE-2021-29431

Sydent is a reference Matrix identity server. Sydent can be induced to send HTTP GET requests to internal systems, due to lack of parameter validation or IP address blacklisting. It is not possible to exfiltrate data or control request headers, but it might be possible to use the attack to perform an internal port enumeration. This issue has been addressed in in 9e57334, 8936925, 3d531ed, 0f00412. A potential workaround would be to use a firewall to ensure that Sydent cannot reach internal HTTP resources.

• CWE-20
• CWE-918

• https://github.com/matrix-org/sydent/commit/0f00412017f25619bc36c264b29ea96808bf310aPatch, Third Party Advisory
• https://github.com/matrix-org/sydent/commit/3d531ed50d2fd41ac387f36d44d3fb2c62dd22d3Patch, Third Party Advisory
• https://github.com/matrix-org/sydent/commit/8936925f561b0c352c2fa922d5097d7245aad00aPatch, Third Party Advisory
• https://github.com/matrix-org/sydent/commit/9e573348d81df8191bbe8c266c01999c9d57cd5fPatch, Third Party Advisory
• https://github.com/matrix-org/sydent/releases/tag/v2.3.0Release Notes, Third Party Advisory
• https://github.com/matrix-org/sydent/security/advisories/GHSA-9jhm-8m8c-c3f4Patch, Third Party Advisory
• https://pypi.org/project/matrix-sydent/Product, Third Party Advisory
• https://github.com/matrix-org/sydent/commit/0f00412017f25619bc36c264b29ea96808bf310aPatch, Third Party Advisory
• https://github.com/matrix-org/sydent/commit/3d531ed50d2fd41ac387f36d44d3fb2c62dd22d3Patch, Third Party Advisory
• https://github.com/matrix-org/sydent/commit/8936925f561b0c352c2fa922d5097d7245aad00aPatch, Third Party Advisory
• https://github.com/matrix-org/sydent/commit/9e573348d81df8191bbe8c266c01999c9d57cd5fPatch, Third Party Advisory
• https://github.com/matrix-org/sydent/releases/tag/v2.3.0Release Notes, Third Party Advisory
• https://github.com/matrix-org/sydent/security/advisories/GHSA-9jhm-8m8c-c3f4Patch, Third Party Advisory
• https://pypi.org/project/matrix-sydent/Product, Third Party Advisory

Published

Apr 15, 2021

Last Modified

Jun 17, 2026

Status

Modified

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