Cloudanix VulnDB

GHSA-46wh-3698-f2cx

Critical · 9.1

Traefik: Deny Rule Bypass via Unauthenticated Malicious gRPC Requests in gRPC-Go Dependency (CVE-2026-33186)

CVSS

9.1

EPSS

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Published

Mar 29, 2026

CISA due date

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The record

There is a potential vulnerability in Traefik due to its dependency on an affected version of gRPC-Go (CVE-2026-33186). A remote, unauthenticated attacker can send gRPC requests with a malformed HTTP/2 `:path` pseudo-header omitting the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server routes such requests correctly, path-based authorization interceptors evaluate the raw non-canonical path and fail to match "deny" rules, allowing the request to bypass the policy entirely if a fallback "allow" rule is present. This CVE hits traefik until Version 3.6.11 and 2.11.41. gRPC-Go has an authorization bypass via missing leading slash in :path

Affected packages

Ecosystem Package Introduced Fixed

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