Synapse pagination denial of service
Priority LOW 23CWE-20Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
Summary
Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00369 30th percentileScored 2026-11-07
Fix Fixed synapse (element-hq): 1.152.1matrix-synapse (PyPI): 1.152.1
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 |
|---|---|---|---|---|---|
| element-hq | synapse | before 1.152.1 | 1.152.1 | Patch available | CNA |
| — | matrix-synapse (PyPI) | before 1.152.1 | 1.152.1 | Patch available | GHSA-6qf2-7x63-mm6v |
- synapse Vendorelement-hq Affected before 1.152.1 Fixed in 1.152.1 Patch available CNA
- matrix-synapse (PyPI) Vendor— Affected before 1.152.1 Fixed in 1.152.1 Patch available GHSA-6qf2-7x63-mm6v
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:element:synapse:*:*:*:*:*:*:*:* | before 1.152.1 | Vulnerable | element-hq |
- cpe:2.3:a:element:synapse:*:*:*:*:*:*:*:* Versions before 1.152.1 Vulnerable ·element-hq
Remediation
- Fix · CNA synapse (element-hq) Fixed in 1.152.1
- Fix · GHSA-6qf2-7x63-mm6v matrix-synapse (PyPI) Fixed in 1.152.1 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-45076
- 2026-10-03 Alias added: GHSA-6qf2-7x63-mm6v
References
More element-hq Synapse vulnerabilities
- TI-2026-32926 Synapse CPU starvation (Denial of Service) CVSS 4.0MEDIUM 6.8
Sources
- CVE-2026-45076 · CVE Program
- CVE-2026-45076 · NVD
- FIRST EPSS
- GHSA-6qf2-7x63-mm6v · GitHub Advisory Database · CC BY 4.0
- CVE-2026-45076 · 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