---
cve: "CVE-2026-48521"
severity: "MEDIUM"
cvss: 5.9
epss: "6.8%"
vendor: "envoyproxy"
kev: false
exploited: false
published: "2026-09-21 20:17:25"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-22T14:36:49+02:00"
---

# CVE-2026-48521

> 5.9 MEDIUM · 🧪 PoC

## Beschreibung

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's ProdClusterManagerFactory::allocateConnPool dereferences transport_socket_options while selecting an HTTP/3 connection pool without first checking whether the pointer is null. LoadBalancerContext implementations used by synthetic, mirror, health-check, and async-client calls can return no transport-socket options. With auto_config and HTTP/3 enabled, routine traffic reaching one of those contexts can crash an Envoy worker. The relevant scope boundary is that the affected branch requires HTTP/3 in the protocol set and a context that supplies no transport-socket options. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Hoch | good |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- 053a8989382dd91542ecf0cef8f379b9cb761cdd (Commit)
- cf413bdb37b36d3ffbe570b8a48760abe2b588f5 (Commit)

## Referenzen

- <https://github.com/envoyproxy/envoy/security/advisories/GHSA-5vff-j9p4-38j3>
- <https://github.com/envoyproxy/envoy/commit/8ef2da8527fcd17388b046c1add4fb47fb5d0868>
- <https://github.com/envoyproxy/envoy/commit/cec4899acf03cf551f28611a5f32385648d95f96>
- <https://github.com/envoyproxy/envoy/commit/e7b4839beef7f43594ce8e94c4563c80db04a8a7>
- <https://github.com/envoyproxy/envoy/commit/f5436f44103fb14cb8ba42a8db0f54a06c98c45a>
- <https://github.com/envoyproxy/envoy/releases/tag/v1.36.10>
- <https://github.com/envoyproxy/envoy/releases/tag/v1.37.6>
- <https://github.com/envoyproxy/envoy/releases/tag/v1.38.4>
- <https://github.com/envoyproxy/envoy/releases/tag/v1.39.1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-48521) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_