{"id":"CVE-2026-48521","state":"PUBLISHED","title":"Envoy: HTTP/3 connection pool selection null-derefs in ProdClusterManagerFactory::allocateConnPool when transport_socket_options is null","description":"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 ProdClusterManagerFactory::allocateConnPool dereferences transport_socket_options while selecting an HTTP/3 connection pool without first checking whether the pointer is null. LoadBalancerContext implementations used by synthetic, mirror, health-check, and async-client calls can return no transport-socket options. With auto_config and HTTP/3 enabled, routine traffic reaching one of those contexts can crash an Envoy worker. The relevant scope boundary is that the affected branch requires HTTP/3 in the protocol set and a context that supplies no transport-socket options. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.","publishedAt":"2026-09-21T19:44:15.389Z","updatedAt":"2026-09-21T20:04:16.440Z","severity":{"score":5.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["envoyproxy envoy"],"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"}]}],"references":["https://github.com/envoyproxy/envoy/security/advisories/GHSA-5vff-j9p4-38j3","https://github.com/envoyproxy/envoy/commit/8ef2da8527fcd17388b046c1add4fb47fb5d0868","https://github.com/envoyproxy/envoy/commit/cec4899acf03cf551f28611a5f32385648d95f96","https://github.com/envoyproxy/envoy/commit/e7b4839beef7f43594ce8e94c4563c80db04a8a7","https://github.com/envoyproxy/envoy/commit/f5436f44103fb14cb8ba42a8db0f54a06c98c45a","https://github.com/envoyproxy/envoy/releases/tag/v1.36.10","https://github.com/envoyproxy/envoy/releases/tag/v1.37.6","https://github.com/envoyproxy/envoy/releases/tag/v1.38.4","https://github.com/envoyproxy/envoy/releases/tag/v1.39.1"],"weaknesses":["CWE-476"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/48xxx/CVE-2026-48521.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-48521","state":"PUBLISHED","datePublished":"2026-09-21T19:44:15.389Z","dateUpdated":"2026-09-21T20:04:16.440Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-21T16:18:10.619Z"},"containers":{"cna":{"title":"Envoy: HTTP/3 connection pool selection null-derefs in ProdClusterManagerFactory::allocateConnPool when transport_socket_options is null","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's ProdClusterManagerFactory::allocateConnPool dereferences transport_socket_options while selecting an HTTP/3 connection pool without first checking whether the pointer is null. LoadBalancerContext implementations used by synthetic, mirror, health-check, and async-client calls can return no transport-socket options. With auto_config and HTTP/3 enabled, routine traffic reaching one of those contexts can crash an Envoy worker. The relevant scope boundary is that the affected branch requires HTTP/3 in the protocol set and a context that supplies no transport-socket options. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1."}],"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"}]}],"references":[{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-5vff-j9p4-38j3","name":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-5vff-j9p4-38j3","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/envoyproxy/envoy/commit/8ef2da8527fcd17388b046c1add4fb47fb5d0868","name":"https://github.com/envoyproxy/envoy/commit/8ef2da8527fcd17388b046c1add4fb47fb5d0868","tags":["x_refsource_MISC"]},{"url":"https://github.com/envoyproxy/envoy/commit/cec4899acf03cf551f28611a5f32385648d95f96","name":"https://github.com/envoyproxy/envoy/commit/cec4899acf03cf551f28611a5f32385648d95f96","tags":["x_refsource_MISC"]},{"url":"https://github.com/envoyproxy/envoy/commit/e7b4839beef7f43594ce8e94c4563c80db04a8a7","name":"https://github.com/envoyproxy/envoy/commit/e7b4839beef7f43594ce8e94c4563c80db04a8a7","tags":["x_refsource_MISC"]},{"url":"https://github.com/envoyproxy/envoy/commit/f5436f44103fb14cb8ba42a8db0f54a06c98c45a","name":"https://github.com/envoyproxy/envoy/commit/f5436f44103fb14cb8ba42a8db0f54a06c98c45a","tags":["x_refsource_MISC"]},{"url":"https://github.com/envoyproxy/envoy/releases/tag/v1.36.10","name":"https://github.com/envoyproxy/envoy/releases/tag/v1.36.10","tags":["x_refsource_MISC"]},{"url":"https://github.com/envoyproxy/envoy/releases/tag/v1.37.6","name":"https://github.com/envoyproxy/envoy/releases/tag/v1.37.6","tags":["x_refsource_MISC"]},{"url":"https://github.com/envoyproxy/envoy/releases/tag/v1.38.4","name":"https://github.com/envoyproxy/envoy/releases/tag/v1.38.4","tags":["x_refsource_MISC"]},{"url":"https://github.com/envoyproxy/envoy/releases/tag/v1.39.1","name":"https://github.com/envoyproxy/envoy/releases/tag/v1.39.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":5.9,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-476","lang":"en","description":"CWE-476: NULL Pointer Dereference","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-21T19:44:15.389Z"},"source":{"advisory":"GHSA-5vff-j9p4-38j3","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-5vff-j9p4-38j3","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-21T20:02:39.214503Z","id":"CVE-2026-48521","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-21T20:04:16.440Z"}}]}}}