CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
SINGLE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:M/Au:S/C:P/I:P/A:N
CVSS3
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
EPSS
Percentile
36.7%
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.
This issue is fixed by #9240.
Outbound requests to the following address ranges can be blocked by a firewall, if unused for internal communication between systems:
::ffff/80
::0000/80
(note that this IP range is considered deprecated by the IETF)2002::/16
(note that this IP range is considered deprecated by the IETF)github.com/advisories/GHSA-5wrh-4jwv-5w78
github.com/matrix-org/synapse/commit/4ca054a4eaa714d0befb4fc30b19a1131e52c9cc
github.com/matrix-org/synapse/pull/9240
github.com/matrix-org/synapse/security/advisories/GHSA-5wrh-4jwv-5w78
github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2021-25.yaml
lists.fedoraproject.org/archives/list/[email protected]/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY
nvd.nist.gov/vuln/detail/CVE-2021-21392
pypi.org/project/matrix-synapse
CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
SINGLE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:M/Au:S/C:P/I:P/A:N
CVSS3
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
EPSS
Percentile
36.7%