CVE-2021-21392 Open redirect via transitional IPv6 addresses on dual-stack networks

2021-04-1221:50:14

CWE-601

GitHub_M

www.cve.org

cve-2021-21392

open redirect

ipv6 addresses

dual-stack networks

synapse

federated instant messaging

voip

python

matrix

github security advisory

CVSS3

6.3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality Impact

LOW

Integrity Impact

HIGH

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:N

AI Score

6.9

Confidence

High

EPSS

0.001

Percentile

36.7%

JSON

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.

CNA Affected

[
  {
    "product": "synapse",
    "vendor": "matrix-org",
    "versions": [
      {
        "status": "affected",
        "version": "< 1.28.0"
      }
    ]
  }
]