{"id":"CVE-2026-56816","title":"io.netty:netty-codec-http3: Netty: Denial of Service due to uncontrolled memory buffering in HTTP/3 (CVE-2026-56816)","summary":"A flaw was found in Netty. An unauthenticated remote attacker can exploit a vulnerability in Netty's `Http3FrameCodec` by sending specially crafted HTTP/3 reserved frames with excessive payload lengths. This can lead to uncontrolled memory…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-770","CWE-400"],"vendor":"Red Hat","product":"Red Hat OpenShift AI (RHOAI)","affected":["openshift_ai_rhoai"],"patched":["io.netty:netty-codec-http3 4.2.16.Final"],"published":"2026-07-21","updated":"2026-09-29","sourceUpdated":"2026-09-29T17:12:38+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-56816.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-56816.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-56816"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2505424"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-56816"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56816"},{"url":"https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b"},{"url":"https://github.com/netty/netty/releases/tag/netty-4.2.16.Final"},{"url":"https://github.com/netty/netty/security/advisories/GHSA-hpcc-26xq-25fv"},{"url":"https://github.com/advisories/GHSA-hpcc-26xq-25fv"}],"tags":["csaf","vex","red-hat","ghsa","maven"],"epss":0.00644,"epssPercentile":0.50659,"aliases":["GHSA-hpcc-26xq-25fv"],"ecosystem":"maven","ingestedAt":"2026-07-22T22:06:57.819Z","slug":"CVE-2026-56816","body":"## Overview\n\nA flaw was found in Netty. An unauthenticated remote attacker can exploit a vulnerability in Netty's `Http3FrameCodec` by sending specially crafted HTTP/3 reserved frames with excessive payload lengths. This can lead to uncontrolled memory buffering, causing memory exhaustion and a denial of service (DoS) for the affected system.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Important · updated 2026-09-29 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-56816.json)\n\n**io.netty:netty-codec-http3: Netty: Denial of Service due to uncontrolled memory buffering in HTTP/3** — rated Important by Red Hat. Released 2026-07-21, updated 2026-09-29.\n\nNot affected:\n\n- Red Hat OpenShift AI (RHOAI)\n- Red Hat OpenShift Dev Spaces\n\n## Remediation\n\nRefer to the advisory for fix availability.\n\n## Package advisory (CVE-2026-56816)\n\nAffected packages:\n\n- `io.netty:netty-codec-http3 < 4.2.16.Final`\n\nPatched in:\n\n- `io.netty:netty-codec-http3 4.2.16.Final`\n\nSource: https://github.com/advisories/GHSA-hpcc-26xq-25fv","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}