Bug 1949111 (CVE-2021-21392) - CVE-2021-21392 matrix-synapse: IP blacklist bypass via transitional IPv6 addresses on dual-stack networks
Summary: CVE-2021-21392 matrix-synapse: IP blacklist bypass via transitional IPv6 add...
Alias: CVE-2021-21392
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1949112
TreeView+ depends on / blocked
Reported: 2021-04-13 12:57 UTC by Michael Kaplan
Modified: 2021-04-13 22:46 UTC (History)
2 users (show)

Fixed In Version: matrix-synapse 1.28.0
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Clone Of:
Last Closed: 2021-04-13 22:46:43 UTC

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Description Michael Kaplan 2021-04-13 12:57:29 UTC
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.

Comment 2 Michael Kaplan 2021-04-13 12:57:51 UTC
Created matrix-synapse tracking bugs for this issue:

Affects: fedora-all [bug 1949112]

Comment 3 Product Security DevOps Team 2021-04-13 22:46:43 UTC
This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.

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