{"id":"UBUNTU-CVE-2026-11404","details":"Cesanta Mongoose before 7.22 contains an out-of-bounds read in the built-in TLS server function mg_tls_server_recv_hello(), which uses an attacker-controlled session_id_len byte from a TLS ClientHello as a buffer index without validating it against the length of received data. A remote, unauthenticated attacker can send a single crafted ClientHello with an oversized session id length to read past the receive buffer, crashing any HTTPS, MQTTS, or WSS service built on MG_TLS_BUILTIN.","modified":"2026-10-17T12:58:04.201061197Z","published":"2026-07-09T16:16:00Z","upstream":["CVE-2026-11404"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-11404"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-11404"},{"type":"REPORT","url":"https://github.com/cesanta/mongoose"},{"type":"REPORT","url":"https://github.com/cesanta/mongoose/commit/c288ac1f38424ffdd4d2fd5e1893fd4962642db3"},{"type":"REPORT","url":"https://github.com/cesanta/mongoose/releases/tag/7.22"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/cesanta-mongoose-out-of-bounds-read-in-mg-tls-builtin-clienthello-session-id-parsing"}],"affected":[{"package":{"name":"mongoose","ecosystem":"Ubuntu:26.10","purl":"pkg:deb/ubuntu/mongoose?arch=source&distro=stonking"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["7.21+ds-1","7.21+ds-2","7.22+ds-1","7.23+ds-1"],"ecosystem_specific":{"binaries":[{"binary_name":"mongoose-webserver-source","binary_version":"7.23+ds-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-11404.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}