{"id":"CVE-2026-97031","published":"2026-10-08T23:17:06.037","lastModified":"2026-10-09T16:35:35.900","description":"Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references. We now reject these as malformed and curb the memory amplification vector as a result.","cvssScore":7.5,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwes":["CWE-405"],"vendors":[],"products":[],"references":[{"url":"https://go.dev/cl/847312","tags":[]},{"url":"https://go.dev/issue/81855","tags":[]},{"url":"https://groups.google.com/g/golang-announce/c/U2fTuyDJznI","tags":[]},{"url":"https://pkg.go.dev/vuln/GO-2026-6607","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"This vulnerability allows attackers to cause memory exhaustion on servers by sending ECH packets with multiple outer extension references, which are not permitted under RFC 9849. The flaw enables a memory amplification attack that can exhaust server resources.","exploitability":"Exploitation requires sending a specially crafted ECH packet with multiple extension references, which is moderately difficult but possible without authentication or user interaction.","blast_radius":"If exploited, this vulnerability could cause widespread server resource exhaustion across affected implementations that process ECH packets, potentially leading to denial of service for legitimate users.","remediation":"Upgrade to the fixed version that properly validates ECH extension references according to RFC 9849 specifications.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["memory-exhaustion","ech","rfc-compliance","dos"],"model":"garnet-coder","analyzedAt":"2026-10-16T09:23:37.388Z"}}