{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-73548", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-08-12T20:53:46.379Z", "datePublished": "2026-09-21T19:35:15.275Z", "dateUpdated": "2026-09-21T19:35:15.275Z"}, "containers": {"cna": {"title": "Envoy: Cross-user response poisoning via a generic (non-WebSocket) HTTP upgrade on Envoy's shared backend pool", "problemTypes": [{"descriptions": [{"cweId": "CWE-444", "lang": "en", "description": "CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-3vhp-c83q-jqc2", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-3vhp-c83q-jqc2"}, {"name": "https://github.com/envoyproxy/envoy/commit/309855626966cff176155c821043ed3b44671361", "tags": ["x_refsource_MISC"], "url": "https://github.com/envoyproxy/envoy/commit/309855626966cff176155c821043ed3b44671361"}, {"name": "https://github.com/envoyproxy/envoy/commit/3c7998545a9c9fb3933a4bc1907d92f0e752bc2b", "tags": ["x_refsource_MISC"], "url": "https://github.com/envoyproxy/envoy/commit/3c7998545a9c9fb3933a4bc1907d92f0e752bc2b"}, {"name": "https://github.com/envoyproxy/envoy/commit/4633b8cce3d15b8734eefe232e30c12b0140b91c", "tags": ["x_refsource_MISC"], "url": "https://github.com/envoyproxy/envoy/commit/4633b8cce3d15b8734eefe232e30c12b0140b91c"}, {"name": "https://github.com/envoyproxy/envoy/commit/bd6711f2617658e28dfa3df3dace6bfe3cfc0766", "tags": ["x_refsource_MISC"], "url": "https://github.com/envoyproxy/envoy/commit/bd6711f2617658e28dfa3df3dace6bfe3cfc0766"}, {"name": "https://github.com/envoyproxy/envoy/releases/tag/v1.36.10", "tags": ["x_refsource_MISC"], "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.36.10"}, {"name": "https://github.com/envoyproxy/envoy/releases/tag/v1.37.6", "tags": ["x_refsource_MISC"], "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.37.6"}, {"name": "https://github.com/envoyproxy/envoy/releases/tag/v1.38.4", "tags": ["x_refsource_MISC"], "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.38.4"}, {"name": "https://github.com/envoyproxy/envoy/releases/tag/v1.39.1", "tags": ["x_refsource_MISC"], "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.39.1"}], "affected": [{"vendor": "envoyproxy", "product": "envoy", "versions": [{"version": "< 1.36.10", "status": "affected"}, {"version": ">= 1.37.0, < 1.37.6", "status": "affected"}, {"version": ">= 1.38.0, < 1.38.4", "status": "affected"}, {"version": ">= 1.39.0, < 1.39.1", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-09-21T19:35:15.275Z"}, "descriptions": [{"lang": "en", "value": "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."}], "source": {"advisory": "GHSA-3vhp-c83q-jqc2", "discovery": "UNKNOWN"}}}}