CVEvulnerability

CVE-2021-21392

6.3 MEDIUM Published 2021-04-12 Modified 2026-06-17 Official page ↗
Status
Modified
Published
2021-04-12
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 ([email protected])
6.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:N
CVSS 3.1 ([email protected])
6.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:N
CVSS 2.0 ([email protected])
4.9 MEDIUM — AV:N/AC:M/Au:S/C:P/I:P/A:N
Weaknesses
CWE-601

Description

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 1.28.0 requests to user provided domains were not restricted to external IP addresses when transitional IPv6 addresses were used. Outbound requests to federation, identity servers, when calculating the key validity for third-party invite events, sending push notifications, and generating URL previews are affected. This could cause Synapse to make requests to internal infrastructure on dual-stack networks. See referenced GitHub security advisory for details and workarounds.

Affected configurations

• matrix synapse (< 1.28.0) • fedoraproject fedora 34

Related

Weakness · CWE (1)

  • CWE-601 URL Redirection to Untrusted Site weakness

References