Bug 2027229 (CVE-2021-41281) - CVE-2021-41281 matrix-synapse: remote overwrite vulnerability
Summary: CVE-2021-41281 matrix-synapse: remote overwrite vulnerability
Alias: CVE-2021-41281
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 2026127 2027230
TreeView+ depends on / blocked
Reported: 2021-11-29 07:20 UTC by Marian Rehak
Modified: 2022-03-06 09:16 UTC (History)
3 users (show)

Fixed In Version:
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Last Closed: 2021-11-29 07:51:23 UTC

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Description Marian Rehak 2021-11-29 07:20:56 UTC
Synapse instances with the media repository enabled can be tricked into downloading a file from a remote server into an arbitrary directory. The last 2 directories and file name of the path are chosen randomly by Synapse and cannot be controlled by an attacker, which limits the impact. Homeservers with the media repository disabled are unaffected. Homeservers with a federation whitelist are also unaffected, since Synapse will check the remote hostname, including the trailing `../`s, against the whitelist. Server administrators should upgrade to 1.47.1 or later. Server administrators using a reverse proxy could, at the expense of losing media functionality, may block the certain endpoints as a workaround. Alternatively, non-containerized deployments can be adapted to use the hardened systemd config.



Comment 1 Marian Rehak 2021-11-29 07:25:20 UTC
Created matrix-synapse tracking bugs for this issue:

Affects: fedora-all [bug 2027230]

Comment 2 Product Security DevOps Team 2021-11-29 07:51:21 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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