Vulnerability · Published Apr 12, 2021 · Assigned by GitHub_M
CVE-2021-21392Open redirect via transitional IPv6 addresses on dual-stack networks
Medium 6.3
In plain English
A medium-severity open redirect in synapse from matrix-org. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 61% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:14 | matrix-synapse | 1.28.0-1 | DEBIAN-CVE-2021-21392 |
| PyPI | matrix-synapse | 1.28.0rc1 | GHSA-5wrh-4jwv-5w78 |
| PyPI | matrix-synapse | 1.28.0 | PYSEC-2021-25 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| matrix-org | synapse | < 1.28.0 |
Weakness: CWE-601 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:N
References
- https://pypi.org/project/matrix-synapse/ x_refsource_MISC
- https://github.com/matrix-org/synapse/security/advisories/GHSA-5wrh-4jwv-5w78 x_refsource_CONFIRM
- https://github.com/matrix-org/synapse/pull/9240 x_refsource_MISC
- FEDORA-2021-a627cfd31e vendor-advisory, x_refsource_FEDORA