Synapse vulnerable to leak of remote user device information
Priority LOW 26CWE-200Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- Low · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-200.
Summary
Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.
Why it matters now
EPSS 0.01196 68th percentileScored 2026-11-07
Fix Fixed synapse (matrix-org): 1.95.1matrix-synapse (PyPI): 1.95.1
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| matrix-org | synapse | before 1.95.1 | 1.95.1 | Patch available | CNA |
| — | matrix-synapse (PyPI) | before 1.95.1 | 1.95.1 | Patch available | GHSA-mp92-3jfm-3575 |
- synapse Vendormatrix-org Affected before 1.95.1 Fixed in 1.95.1 Patch available CNA
- matrix-synapse (PyPI) Vendor— Affected before 1.95.1 Fixed in 1.95.1 Patch available GHSA-mp92-3jfm-3575
CPE configurations NVD · 3
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:* | before 1.95.1 | Vulnerable | matrix-org |
| cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:* | 38 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:* | 39 | Vulnerable | Fedoraproject |
- cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:* Versions before 1.95.1 Vulnerable ·matrix-org
- cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:* Versions 38 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:* Versions 39 Vulnerable ·Fedoraproject
Remediation
- Fix · CNA synapse (matrix-org) Fixed in 1.95.1
- Fix · GHSA-mp92-3jfm-3575 matrix-synapse (PyPI) Fixed in 1.95.1 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2023-43796
- 2026-10-03 Alias added: GHSA-mp92-3jfm-3575
References
Advisory 2
Other 7
- https://lists.fedoraproject.org/archives/list/[email protected]/message/VH3RNC5ZPQZ4OKPSL4E6BBJSZOQLGDEY/
- https://lists.fedoraproject.org/archives/list/[email protected]/message/2IDEEZMFJBDLTFHQUTZRJJNCOZGQ2ZVS/
- https://security.gentoo.org/glsa/202401-12
- https://github.com/matrix-org/synapse
- https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2023-230.yaml
- https://lists.fedoraproject.org/archives/list/[email protected]/message/2IDEEZMFJBDLTFHQUTZRJJNCOZGQ2ZVS
- https://lists.fedoraproject.org/archives/list/[email protected]/message/VH3RNC5ZPQZ4OKPSL4E6BBJSZOQLGDEY
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-2023-43796 · CVE Program
- CVE-2023-43796 · NVD
- FIRST EPSS
- GHSA-mp92-3jfm-3575 · GitHub Advisory Database · CC BY 4.0
- CVE-2023-43796 · 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