CVE-2026-73548

{"id": "CVE-2026-73548", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-73548", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-24T22:34:49.061262Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 3.6, "exploitabilityScore": 3.9}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "envoyproxy", "product": "envoy", "versions": [{"status": "affected", "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"}]}]}], "published": "2026-09-21T20:17:28.397", "references": [{"url": "https://github.com/envoyproxy/envoy/commit/309855626966cff176155c821043ed3b44671361", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/envoyproxy/envoy/commit/3c7998545a9c9fb3933a4bc1907d92f0e752bc2b", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/envoyproxy/envoy/commit/4633b8cce3d15b8734eefe232e30c12b0140b91c", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/envoyproxy/envoy/commit/bd6711f2617658e28dfa3df3dace6bfe3cfc0766", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/envoyproxy/envoy/releases/tag/v1.36.10", "tags": ["Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/envoyproxy/envoy/releases/tag/v1.37.6", "tags": ["Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/envoyproxy/envoy/releases/tag/v1.38.4", "tags": ["Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/envoyproxy/envoy/releases/tag/v1.39.1", "tags": ["Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-3vhp-c83q-jqc2", "tags": ["Exploit", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-3vhp-c83q-jqc2", "tags": ["Exploit", "Vendor Advisory"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-444"}]}], "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."}], "lastModified": "2026-10-05T14:19:45.960", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "6A420B14-9ADA-4F6B-ACAA-3045E8690F04", "versionEndExcluding": "1.36.10"}, {"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "1AD376F3-22D7-4BFB-B00C-BD68F464436F", "versionEndExcluding": "1.37.6", "versionStartIncluding": "1.37.0"}, {"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "840E030F-8746-4DBD-87C0-5DF7896294CC", "versionEndExcluding": "1.38.4", "versionStartIncluding": "1.38.0"}, {"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "B5C1C594-8142-4F51-BE50-1AF50FD07129", "versionEndExcluding": "1.39.1", "versionStartIncluding": "1.39.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}