{"id":"CVE-2026-78663","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-78663","generatedAt":"2026-10-28T01:51:43.882Z","title":"A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection).","description":"The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler reads the buffered data. A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.","published":"2026-10-08T23:17:04.000Z","lastModified":"2026-10-09T17:16:49.000Z","status":"Awaiting Analysis","sourceIdentifier":"security@golang.org","cvss":{"version":"3.1","score":9.1,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H"},"cwe":["CWE-675"],"affected":[],"epss":{"score":0.00622,"percentile":0.49513,"date":"2026-10-26","history":[{"date":"2026-10-09","score":0.00248,"percentile":0.14768}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.62%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"scored","label":"Newly scored","at":"2026-10-09T19:00:22.000Z","detail":{"from":null,"score":"9.1","severity":"CRITICAL","fromSeverity":null},"summary":"Now scored CVSS 9.1 CRITICAL."},{"kind":"new","label":"New CVE","at":"2026-10-08T23:17:04.000Z","detail":{"score":null,"severity":null,"publishedAt":"2026-10-08T23:17:03.647Z"},"summary":"New CVE, critical severity (CVSS 9.1)."}],"references":[{"url":"https://go.dev/cl/847187","source":"security@golang.org"},{"url":"https://go.dev/cl/847310","source":"security@golang.org"},{"url":"https://go.dev/issue/81743","source":"security@golang.org"},{"url":"https://groups.google.com/g/golang-announce/c/U2fTuyDJznI","source":"security@golang.org"},{"url":"https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs","source":"security@golang.org"},{"url":"https://pkg.go.dev/vuln/GO-2026-6612","source":"security@golang.org"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-78663","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}