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Fencer Vulns
medium 6.5

CVE-2022-31052 json

URL previews can crash Synapse media repositories or Synapse monoliths

published 2022-06-28 4 y ago modified 2026-06-17 4 mo ago also GHSA-22p3-qrh9-cx32 , PYSEC-2022-224 , EUVD-2022-0153

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.7%
EPSS 1.7% chance of exploitation in 30 days, percentile 76%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi matrix-synapse 1.61.1
  • matrix synapse 1.61.1
  • matrix-synapse openSUSE Tumbleweed 1.61.1-1.1

opensuse advisories openSUSE-SU-2024:12160-1

  • synapse Alpine 3.24, Alpine 3.23, Alpine 3.22 +6 more 1.61.1-r0

alpine advisories ALPINE-CVE-2022-31052

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2022-31052 updated cvss 6.5

synapse: DoS due to unbounded recusion

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
18 mo ago

Exploit prediction

1.66% chance of exploitation in the next 30 days, higher than 76% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 3.5 AV:N/AC:M/Au:S/C:N/I:N/A:P
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi matrix-synapse
<1.61.1
1.61.1

Affected products

  • matrix-org synapse

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.