{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-8718","assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","state":"PUBLISHED","assignerShortName":"zephyr","dateReserved":"2026-05-15T21:27:25.564Z","datePublished":"2026-08-10T22:40:26.836Z","dateUpdated":"2026-08-12T18:49:59.886Z"},"containers":{"cna":{"providerMetadata":{"orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","shortName":"zephyr","dateUpdated":"2026-08-10T22:40:26.836Z"},"title":"Out-of-bounds write in DTLS peer Connection ID getsockopt (`TLS_DTLS_PEER_CID_VALUE`) in Zephyr net sockets/TLS","descriptions":[{"lang":"en","value":"tls_opt_dtls_peer_connection_id_value_get() in subsys/net/lib/sockets/sockets_tls.c, which handles getsockopt(SOL_TLS, TLS_DTLS_PEER_CID_VALUE), passed the caller-supplied optval directly to mbedtls_ssl_get_peer_cid() without verifying the buffer was at least MBEDTLS_SSL_CID_OUT_LEN_MAX (default 32) bytes. mbedtls_ssl_get_peer_cid() copies the peer-negotiated DTLS Connection ID (length 1..MBEDTLS_SSL_CID_OUT_LEN_MAX) into that buffer without a destination-size parameter, so a caller-supplied optlen smaller than the CID causes a write of up to 31 bytes past the buffer end.\n\nIn CONFIG_USERSPACE builds the getsockopt syscall verifier (z_vrfy_zsock_getsockopt) bounce-buffers the user's optval into a kernel allocation of exactly optlen bytes (k_usermode_alloc_from_copy -> z_thread_malloc), so an unprivileged user thread that passes a small optlen on a connected DTLS socket with Connection ID enabled induces a kernel-heap buffer overflow, with the overflowing content being the remote peer's CID.\n\nThe defect requires CONFIG_MBEDTLS_SSL_DTLS_CONNECTION_ID, an established DTLS session with a negotiated peer CID, and (for the kernel-crossing case) CONFIG_USERSPACE. Introduced when the TLS_DTLS_CID option was added (v3.5.0).\n\nThe fix rejects callers whose optlen is below MBEDTLS_SSL_CID_OUT_LEN_MAX with -EINVAL."}],"affected":[{"vendor":"zephyrproject","product":"zephyr","collectionURL":"https://github.com/zephyrproject-rtos/zephyr","packageName":"zephyr","defaultStatus":"unaffected","programFiles":["subsys/net/lib/sockets/sockets_tls.c"],"versions":[{"version":"3.5.0","status":"affected","versionType":"semver","lessThan":"4.4.1"}]}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/aa317825a55a401315e8e17f620c70c02e8f176d","name":"Fix commit","tags":["patch"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-p3r6-mx6c-33gq","name":"GHSA-p3r6-mx6c-33gq"}],"metrics":[{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H","baseScore":8.4,"baseSeverity":"HIGH"}}],"problemTypes":[{"descriptions":[{"lang":"en","description":"bounds","cweId":"CWE-787","type":"CWE"}]}],"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-p3r6-mx6c-33gq","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-12T18:49:17.354008Z","id":"CVE-2026-8718","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-08-12T18:49:59.886Z"}}]}}