---
cve: "CVE-2026-84303"
severity: "MEDIUM"
cvss: 6.3
epss: "0.3%"
vendor: "grpc"
kev: false
exploited: false
published: "2026-09-01 19:17:30"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-21T14:47:56+02:00"
---

# CVE-2026-84303

> 6.3 MEDIUM · 🧪 PoC

## Beschreibung

gRPC-Go is the Go language implementation of gRPC. Prior to 1.83.1, the xDS RBAC HTTP filter in internal/xds/httpfilter/rbac/rbac.go does not lowercase header matcher names in normalizeHeaderMatcher even though incoming metadata keys are lowercase. A DENY policy using a mixed-case name such as X-Role or User-Agent therefore does not match and fails open, allowing requests that should be rejected. The same case mismatch permits :Scheme or Grpc-Status to evade gRFC A41 validation and prevents Host from being rewritten to :authority. This issue is fixed in version 1.83.1.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- db9482836c298f234c896cf82ab68cafc78237f8 (Commit)
- ebba6f3f1b206e2b4dc4d1d5a96d18430302c2fe (Commit)

## Referenzen

- <https://github.com/grpc/grpc-go/security/advisories/GHSA-qc2q-p7wx-3px3>
- <https://github.com/grpc/grpc-go/pull/9332>
- <https://github.com/grpc/grpc-go/pull/9335>
- <https://github.com/grpc/grpc-go/commit/db9482836c298f234c896cf82ab68cafc78237f8>
- <https://github.com/grpc/grpc-go/commit/ebba6f3f1b206e2b4dc4d1d5a96d18430302c2fe>
- <https://github.com/grpc/grpc-go/releases/tag/v1.83.1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-84303) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_