Bug 2102872 (CVE-2022-31052) - CVE-2022-31052 synapse: DoS due to unbounded recusion
Summary: CVE-2022-31052 synapse: DoS due to unbounded recusion
Alias: CVE-2022-31052
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 2120487
Blocks: 2102873
TreeView+ depends on / blocked
Reported: 2022-06-30 21:17 UTC by Sage McTaggart
Modified: 2022-09-02 14:25 UTC (History)
4 users (show)

Fixed In Version:
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Clone Of:
Last Closed: 2022-09-02 14:25:50 UTC

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Description Sage McTaggart 2022-06-30 21:17:19 UTC
Synapse is an open source home server implementation for the Matrix chat network. In versions prior to 1.61.1 URL previews of some web pages can exhaust the available stack space for the Synapse process due to unbounded recursion. This is sometimes recoverable and leads to an error for the request causing the problem, but in other cases the Synapse process may crash altogether. It is possible to exploit this maliciously, either by malicious users on the homeserver, or by remote users sending URLs that a local user's client may automatically request a URL preview for. Remote users are not able to exploit this directly, because the URL preview endpoint is authenticated. Deployments with `url_preview_enabled: false` set in configuration are not affected. Deployments with `url_preview_enabled: true` set in configuration **are** affected. Deployments with no configuration value set for `url_preview_enabled` are not affected, because the default is `false`. Administrators of homeservers with URL previews enabled are advised to upgrade to v1.61.1 or higher. Users unable to upgrade should set `url_preview_enabled` to false.


Comment 1 Sandipan Roy 2022-08-23 04:41:33 UTC
Created synapse tracking bugs for this issue:

Affects: fedora-all [bug 2120487]

Comment 2 Product Security DevOps Team 2022-09-02 14:25:48 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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