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HTTP Request Smuggling Affecting kuma-envoy-1.38 package, versions <1.38.4-r0

Severity

 Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.46% (39th percentile)

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  • Snyk IDSNYK-MINIMOSLATEST-KUMAENVOY138-20269679
  • published30 Sept 2026
  • disclosed21 Sept 2026
Report a new vulnerability Found a mistake?

Introduced: 21 Sep 2026

NewCVE-2026-73548  (opens in a new tab)
CWE-444  (opens in a new tab)

How to fix?

Upgrade Minimos:latest kuma-envoy-1.38 to version 1.38.4-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kuma-envoy-1.38 package and not the kuma-envoy-1.38 package as distributed by Minimos. See How to fix? for Minimos:latest relevant fixed versions and status.

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 forwards data for a configured non-WebSocket HTTP upgrade before the upstream accepts the upgrade. An unauthenticated HTTP/2 client can place a complete HTTP/1.1 request in extended CONNECT data; Envoy downgrades the request, writes the data unframed to a keep-alive HTTP/1.1 upstream, and returns the socket to the shared pool while the smuggled response remains queued. A different downstream client can then receive the attacker's response. The relevant scope boundary is that webSocket upgrades, plain CONNECT, disabled backend keep-alive, per-downstream pools, and max_requests_per_connection set to 1 are not affected by the demonstrated path. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.