Synapse up to 1.61.0 URL Preview recursion

Summaryinfo

A vulnerability classified as problematic was found in Synapse up to 1.61.0. This issue affects some unknown processing of the component URL Preview Handler. Executing a manipulation can lead to recursion. This vulnerability appears as CVE-2022-31052. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as problematic was found in Synapse up to 1.61.0. This vulnerability affects an unknown function of the component URL Preview Handler. The manipulation with an unknown input leads to a recursion vulnerability. The CWE definition for the vulnerability is CWE-674. The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. As an impact it is known to affect availability. CVE summarizes:

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.

The weakness was presented 06/28/2022 as GHSA-22p3-qrh9-cx32. The advisory is shared for download at github.com. This vulnerability was named CVE-2022-31052 since 05/18/2022. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 1.61.1 eliminates this vulnerability. Applying the patch fa1308061802ac7b7d20e954ba7372c5ac292333 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Name

• Synapse

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21
• 1.22
• 1.23
• 1.24
• 1.25
• 1.26
• 1.27
• 1.28
• 1.29
• 1.30
• 1.31
• 1.32
• 1.33
• 1.34
• 1.35
• 1.36
• 1.37
• 1.38
• 1.39
• 1.40
• 1.41
• 1.42
• 1.43
• 1.44
• 1.45
• 1.46
• 1.47
• 1.48
• 1.49
• 1.50
• 1.51
• 1.52
• 1.53
• 1.54
• 1.55
• 1.56
• 1.57
• 1.58
• 1.59
• 1.60
• 1.61.0

License

• open-source

CPE 2.3info

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CPE 2.2info

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