Bug 2102872 (CVE-2022-31052)

Summary:	CVE-2022-31052 synapse: DoS due to unbounded recusion
Product:	[Other] Security Response	Reporter:	Sage McTaggart <amctagga>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED UPSTREAM	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	michel, mtasaka, renich, tonet666p
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2022-09-02 14:25:50 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2120487
Bug Blocks:	2102873

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.

https://github.com/matrix-org/synapse/security/advisories/GHSA-22p3-qrh9-cx32
https://spec.matrix.org/v1.2/client-server-api/#get_matrixmediav3preview_url
https://github.com/matrix-org/synapse/commit/fa1308061802ac7b7d20e954ba7372c5ac292333

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.