Medium · published September 22, 2026
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 URL normalization does not recognize dot and dotdot path segments when they carry semicolon parameters. A request such as /user/..;foo=bar/admin is therefore not canonicalized to /admin even when path normalization is enabled. If an upstream interprets the segment according to RFC 3986 while Envoy applies routing or RBAC to the uncollapsed path, a remote client can cause path confusion and bypass path-based security policy. The relevant scope boundary is that the security consequence depends on a downstream/upstream path interpretation mismatch or a path-based Envoy decision. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.
| Product | Versions | Fixed in |
|---|---|---|
| envoyproxy/envoy | < 1.36.10 | 1.36.10 |
| envoyproxy/envoy | ≥ 1.37.0, < 1.37.6 | 1.37.6 |
| envoyproxy/envoy | ≥ 1.38.0, < 1.38.4 | 1.38.4 |
| envoyproxy/envoy | ≥ 1.39.0, < 1.39.1 | 1.39.1 |