{"schema":"threatline.record/2","record":{"id":"CVE-2026-78663","aliases":[],"summary":"Double flow control refund on HTTP/2 server streams in net/http","details":"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.","categories":["Unclassified"],"product":"net/http","vendor":"Go standard library","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-78663","source_modified_at":"2026-10-09T16:42:50.839Z","fetched_at":"2026-10-23T18:48:36.087640Z","product":"net/http","vendor":"Go standard library","versions":[{"version":"0","lessThan":"1.26.9","status":"affected","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-78663","source_modified_at":"2026-10-09T16:42:50.839Z","fetched_at":"2026-10-23T18:48:36.087640Z","product":"net/http/internal/http2","vendor":"Go standard library","versions":[{"version":"1.27.0-0","lessThan":"1.27.2","status":"affected","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-78663","source_modified_at":"2026-10-09T16:42:50.839Z","fetched_at":"2026-10-23T18:48:36.087640Z","product":"golang.org/x/net/http2","vendor":"golang.org/x/net","versions":[{"version":"0","lessThan":"0.60.0","status":"affected","versionType":"semver"}],"defaultStatus":"unaffected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-78663","source_modified_at":"2026-10-09T16:42:50.839Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"net/http","ecosystem":null},"version":"1.26.9","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-78663","source_modified_at":"2026-10-09T16:42:50.839Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"net/http/internal/http2","ecosystem":null},"version":"1.27.2","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-78663","source_modified_at":"2026-10-09T16:42:50.839Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"golang.org/x/net/http2","ecosystem":null},"version":"0.60.0","basis":"first unaffected version stated in the CVE record"}],"cvss":9.1,"severity":"Critical","kev":{"listed":false},"epss":{"probability":0.00574,"percentile":0.46678,"score_date":"2026-10-23"},"published_at":"2026-10-08T22:53:59.772Z","modified_at":"2026-10-09T16:42:50.839Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-78663","fetched_at":"2026-10-23T18:48:36.087640Z","source_modified_at":"2026-10-09T16:42:50.839Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-78663","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://go.dev/cl/847187"},{"source":"CVE List","url":"https://go.dev/cl/847310"},{"source":"CVE List","url":"https://go.dev/issue/81743"},{"source":"CVE List","url":"https://groups.google.com/g/golang-announce/c/U2fTuyDJznI"},{"source":"CVE List","url":"https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs"},{"source":"CVE List","url":"https://pkg.go.dev/vuln/GO-2026-6612"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CISA ADP","ssvc":{"exploitation":"none","automatable":"yes","technical_impact":"total","assessed_at":"2026-10-09T16:40:08.220862Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-10-09T16:42:50.839Z","content_hash":"6ab638790f3257574e3e52587d3e1b088c16affb4909b20cd8a5a94654770fac"}}