{"id":"CVE-2026-50009","aliases":["GHSA-cq4q-cv5g-r8q5"],"url":"https://o3.security/vulnerability/CVE-2026-50009","summary":"Netty QUIC stateless reset token material exposed through header-visible connection IDs","details":"### Summary\nNetty QUIC exposes the stateless reset token on the network path when using the default HMAC-based connection-ID and stateless-reset-token generators. The reset token for the server's current source connection ID can be derived from bytes that appear as the connection ID in QUIC headers after a source-CID rotation. An on-path attacker observing the headers can use the token to perform a Denial of Service by sending a spoofed Stateless Reset packet.\n\n### Details\nThe sign-based connection ID generator (HmacSignQuicConnectionIdGenerator) and reset token generator (HmacSignQuicResetTokenGenerator) both evaluate HMAC-SHA256 with the same JVM-wide static key (io.netty.handler.codec.quic.Hmac).\n\nDuring source CID rotation (QuicheQuicChannel.newSourceConnectionIds), the current server source CID C is used as input to produce the next CID N. The stateless reset token for C is defined over HMAC(K, C), specifically the first 16 bytes. The next CID N is the first L bytes of the same digest, where L = |C|.\n\nWhenever L ≥ 16, the first 16 bytes of N are exactly the stateless reset token for C. Because N is carried in QUIC headers as a connection ID, an observer can read the headers and learn the reset token without decrypting the payload.\n\nThis directly violates RFC 9000\nhttps://datatracker.ietf.org/doc/html/rfc9000#name-calculating-a-stateless-res: `The stateless reset token MUST be difficult to guess.`\nAdditionally https://datatracker.ietf.org/doc/html/rfc9000#name-stateless-reset-oracle\n\n### Impact\nInformation Disclosure and Denial of Service. An on-path attacker can obtain the stateless reset token from the connection ID header and attempt to abruptly close the client side of the connection by sending a spoofed Stateless Reset datagram.","published":"2026-06-12T14:47:09.748Z","modified":"2026-10-21T02:58:24.483713155Z","cvss":{"score":4.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L"},"epss":{"score":0.00204,"percentile":0.10531,"asOf":"2026-09-16"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Maven","name":"io.netty:netty-codec-classes-quic","fixedVersion":"4.2.15.Final"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.2.15.Final"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50009.json"},{"type":"ADVISORY","url":"https://github.com/netty/netty/security/advisories/GHSA-cq4q-cv5g-r8q5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-50009"},{"type":"PACKAGE","url":"https://github.com/netty/netty"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:58:24.483713155Z"}}