---
cve: "CVE-2025-61672"
severity: "MEDIUM"
cvss: 5.3
epss: "0.5%"
vendor: "element-hq"
kev: false
exploited: false
published: "2025-10-08 15:16:25"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-21T08:49:38+02:00"
---

# CVE-2025-61672

> 5.3 MEDIUM · 🧪 PoC

## Beschreibung

Synapse is an open source Matrix homeserver implementation. Lack of validation for device keys in Synapse before 1.138.3 and in Synapse 1.139.0 allow an attacker registered on the victim homeserver to degrade federation functionality, unpredictably breaking outbound federation to other homeservers. The issue is patched in Synapse 1.138.3, 1.138.4, 1.139.1, and 1.139.2. Note that even though 1.138.3 and 1.139.1 fix the vulnerability, they inadvertently introduced an unrelated regression. For this reason, the maintainers of Synapse recommend skipping these releases and upgrading straight to 1.138.4 and 1.139.2.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 527e831b61bcf04106b6338b53048ec3986be7c0 (Commit)

## Referenzen

- <https://github.com/element-hq/synapse/security/advisories/GHSA-fh66-fcv5-jjfr>
- <https://github.com/element-hq/synapse/pull/17097>
- <https://github.com/element-hq/synapse/commit/26aaaf9e48fff80cf67a20c691c75d670034b3c1>
- <https://github.com/element-hq/synapse/commit/7069636c2d6d1ef2022287addf3ed8b919ef2740>
- <https://github.com/element-hq/synapse/releases/tag/v1.138.3>
- <https://github.com/element-hq/synapse/releases/tag/v1.139.1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2025-61672) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_