URL previews can crash Synapse media repositories or Synapse monoliths
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-674.
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| matrix-org | synapse | before 1.61.1 | 1.61.1 | Patch available | CNA |
| — | matrix-synapse (PyPI) | before 1.61.1 | 1.61.1 | Patch available | GHSA-22p3-qrh9-cx32 |
- synapse Vendormatrix-org Affected before 1.61.1 Fixed in 1.61.1 Patch available CNA
- matrix-synapse (PyPI) Vendor— Affected before 1.61.1 Fixed in 1.61.1 Patch available GHSA-22p3-qrh9-cx32
CPE configurations NVD · 3
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:* | before 1.61.1 | Vulnerable | matrix-org |
| cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* | 35 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:* | 36 | Vulnerable | Fedoraproject |
- cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:* Versions before 1.61.1 Vulnerable ·matrix-org
- cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* Versions 35 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:* Versions 36 Vulnerable ·Fedoraproject
Remediation
- Fix · CNA synapse (matrix-org) Fixed in 1.61.1
- Fix · GHSA-22p3-qrh9-cx32 matrix-synapse (PyPI) Fixed in 1.61.1 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2022-31052
- 2026-10-03 Alias added: GHSA-22p3-qrh9-cx32
References
Advisory 5
Other 4
- https://github.com/matrix-org/synapse
- https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2022-224.yaml
- https://lists.fedoraproject.org/archives/list/[email protected]/message/7EARKKJZ2W7WUITFDT4EG4NVATFYJQHF
- https://lists.fedoraproject.org/archives/list/[email protected]/message/QGSDQ4YAITCUACAB7SXQZDJIU3IQ4CJD
More matrix-org Synapse vulnerabilities
- TI-2023-15617 Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites CVSS 3.1MEDIUM 5.0
- TI-2024-35327 Synapse allows a a malformed invite to break the invitee's `/sync` CVSS 4.0HIGH 8.7
- TI-2019-13571 Matrix Synapse before 1.5.0 mishandles signature checking on some federation APIs. CVSS 3.1CRITICAL 9.8
- TI-2024-36056 Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders CVSS 4.0HIGH 8.2
- TI-2024-35318 Synapse allows unsupported content types to lead to memory exhaustion CVSS 4.0HIGH 8.2
- TI-2018-11846 Matrix Synapse before 0.33.3.1 allows remote attackers to spoof events and possibly have… CVSS 3.0HIGH 8.8
Sources
- CVE-2022-31052 · CVE Program
- CVE-2022-31052 · NVD
- FIRST EPSS
- GHSA-22p3-qrh9-cx32 · GitHub Advisory Database · CC BY 4.0
- CVE-2022-31052 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences