Synapse does not apply enough checks to servers requesting auth events of events in a room
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Impact type
- Information disclosure, Security bypass
- Confidentiality · integrity · availability
- Low · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-200 and CWE-862.
Summary
Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. The Matrix Federation API allows remote homeservers to request the authorization events in a room. This is necessary so that a homeserver receiving some events can validate that those events are legitimate and permitted in their room. However, in versions of Synapse up to and including 1.68.0, a Synapse homeserver answering a query for authorization events does not sufficiently check that the requesting server should be able to access them. The issue was patched in Synapse 1.69.0. Homeserver administrators are advised to upgrade.
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 1.69.0 | 1.69.0 | Patch available | CNA |
| — | matrix-synapse (PyPI) | before 1.69.0 | 1.69.0 | Patch available | GHSA-45cj-f97f-ggwv |
- synapse Vendormatrix-org Affected before 1.69.0 Fixed in 1.69.0 Patch available CNA
- matrix-synapse (PyPI) Vendor— Affected before 1.69.0 Fixed in 1.69.0 Patch available GHSA-45cj-f97f-ggwv
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:* | before 1.69.0 | Vulnerable | matrix-org |
- cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:* Versions before 1.69.0 Vulnerable ·matrix-org
Remediation
- Fix · CNA synapse (matrix-org) Fixed in 1.69.0
- Fix · GHSA-45cj-f97f-ggwv matrix-synapse (PyPI) Fixed in 1.69.0 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2022-39335
- 2026-10-03 Alias added: GHSA-45cj-f97f-ggwv
- 2026-10-25 EPSS moved to the 50th–90th percentile
References
Advisory 2
Other 5
- https://github.com/matrix-org/synapse/issues/13288
- https://lists.fedoraproject.org/archives/list/[email protected]/message/T2MBNMZAFY4RCZL2VGBGAPKGB4JUPZVS/
- https://github.com/matrix-org/synapse
- https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2023-65.yaml
- https://lists.fedoraproject.org/archives/list/[email protected]/message/T2MBNMZAFY4RCZL2VGBGAPKGB4JUPZVS
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-2022-39335 · CVE Program
- CVE-2022-39335 · NVD
- FIRST EPSS
- GHSA-45cj-f97f-ggwv · GitHub Advisory Database · CC BY 4.0
- CVE-2022-39335 · 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