{"id":"CVE-2026-50560","aliases":["GHSA-563q-j3cm-6jxm"],"url":"https://o3.security/vulnerability/CVE-2026-50560","summary":"Netty susceptible to HTTP/2 Reset Attack with different on-the-wire signature","details":"### Summary\n\nNetty HTTP/2 max header size handling produces attack similar to HTTP/2 Rapid Reset.\n\n### Details\n\nThere is a setting in the http2 specification called `SETTINGS_MAX_HEADER_LIST_SIZE`. According to[ the RFC](https://www.rfc-editor.org/rfc/rfc9113.html#name-defined-settings): “This advisory setting informs a peer of the maximum field section size that the sender is prepared to accept, in units of octets.”\n\nWhen a client sends that setting to Netty, it appears that Netty will behave as follows:\n\n- Read the request\n- Proxy the request to the origin\n- Attempt to produce a response\n- Create an exception while writing the headers for the response\n\nFunctionally, this should be similar to the http2 reset attack, but with a different on-the-wire signature.\n\n## Remediation\n\nWhen speaking with clients, Netty should potentially treat this as “advisory” and ignore it.  It would be best to ignore the SETTINGS_MAX_HEADER_LIST_SIZE setting from clients (or ignore it when sending to clients). According to the spec, a server does not need to honor this advisory setting, and it appears that other http/2 implementations ignore it when acting as a server.\n\n### Impact\n\nThis is a DDoS attack similar to the HTTP/2 Rapid Reset Attack.\n\n## Credit\nJonathan Looney (Engineering, Netflix)\n\n## Contact\nAshley Tolbert (Security, Netflix) - artolbert@netflix.com","published":"2026-06-12T14:59:59.901Z","modified":"2026-10-21T02:30:15.163626765Z","cvss":null,"epss":{"score":0.00302,"percentile":0.22682,"asOf":"2026-09-13"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Maven","name":"io.netty:netty-codec-http2","fixedVersion":"4.2.15.Final"},{"ecosystem":"Maven","name":"io.netty:netty-codec-http2","fixedVersion":"4.1.135.Final"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.1.135.Final"},{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final"},{"type":"WEB","url":"https://www.rfc-editor.org/rfc/rfc9113.html#name-defined-settings"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50560.json"},{"type":"ADVISORY","url":"https://github.com/netty/netty/security/advisories/GHSA-563q-j3cm-6jxm"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-50560"},{"type":"PACKAGE","url":"https://github.com/netty/netty"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:30:15.163626765Z"}}