{"id":"CVE-2026-48521","title":"Envoy is an open source edge and service proxy designed for cloud-native applications","summary":"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 selectin…","severity":"medium","cvss":5.9,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-476"],"vendor":"envoyproxy","product":"envoy","affected":["envoy < 1.36.10","envoy >= 1.37.0, < 1.37.6","envoy >= 1.38.0, < 1.38.4","envoy >= 1.39.0, < 1.39.1"],"published":"2026-09-21","updated":"2026-09-23","sourceUpdated":"2026-09-23T18:12:04.247","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-48521","references":[{"url":"https://github.com/envoyproxy/envoy/commit/8ef2da8527fcd17388b046c1add4fb47fb5d0868","label":"security-advisories@github.com"},{"url":"https://github.com/envoyproxy/envoy/commit/cec4899acf03cf551f28611a5f32385648d95f96","label":"security-advisories@github.com"},{"url":"https://github.com/envoyproxy/envoy/commit/e7b4839beef7f43594ce8e94c4563c80db04a8a7","label":"security-advisories@github.com"},{"url":"https://github.com/envoyproxy/envoy/commit/f5436f44103fb14cb8ba42a8db0f54a06c98c45a","label":"security-advisories@github.com"},{"url":"https://github.com/envoyproxy/envoy/releases/tag/v1.36.10","label":"security-advisories@github.com"},{"url":"https://github.com/envoyproxy/envoy/releases/tag/v1.37.6","label":"security-advisories@github.com"},{"url":"https://github.com/envoyproxy/envoy/releases/tag/v1.38.4","label":"security-advisories@github.com"},{"url":"https://github.com/envoyproxy/envoy/releases/tag/v1.39.1","label":"security-advisories@github.com"},{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-5vff-j9p4-38j3","label":"security-advisories@github.com"},{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-5vff-j9p4-38j3","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48521.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-48521"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2512093"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-48521"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48521"}],"tags":["nvd","cve.org","exploit-available","csaf","vex","red-hat"],"epss":0.00699,"epssPercentile":0.51048,"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-21T20:02:39.214503Z"},"ingestedAt":"2026-09-21T19:51:58.868Z","slug":"CVE-2026-48521","body":"## Overview\n\nEnvoy 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-22 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48521.json)","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":32.5,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":208784,"id":"CVE-2026-48521","ts":1790024015149,"field":"exploit_available","old":"false","new":"true"}]}