Bug 1949109 (CVE-2021-21393) - CVE-2021-21393 matrix-synapse: Denial of service (via resource exhaustion) due to improper input validation on groups/communities endpoints
Summary: CVE-2021-21393 matrix-synapse: Denial of service (via resource exhaustion) du...
Alias: CVE-2021-21393
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1949110
TreeView+ depends on / blocked
Reported: 2021-04-13 12:55 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 22:46:41 UTC

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Description Michael Kaplan 2021-04-13 12:55:52 UTC
In Synapse before version 1.28.0 Synapse is missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion. Note that the groups feature is not part of the Matrix specification and the chosen maximum lengths are arbitrary. Not all clients might abide by them. Refer to referenced GitHub security advisory for additional details including workarounds.

Comment 2 Michael Kaplan 2021-04-13 12:56:12 UTC
Created matrix-synapse tracking bugs for this issue:

Affects: fedora-all [bug 1949110]

Comment 3 Product Security DevOps Team 2021-04-13 22:46:41 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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