{"schema":"threatline.record/2","record":{"id":"CVE-2026-18415","aliases":["GHSA-j76j-jrjc-xgvp"],"summary":"Out-of-bounds write in the IEEE 802.15.4 L2 transmit path for oversized non-6LoWPAN frames","details":"ieee802154_send() in subsys/net/l2/ieee802154/ieee802154.c copies the outgoing packet into a single fixed 125-byte transmit buffer (tx_frame_buf_pool, sized IEEE802154_MTU). In builds with CONFIG_NET_L2_IEEE802154_FRAGMENT enabled (the default whenever CONFIG_NET_6LO is set), the branch taken when 6LoWPAN fragmentation is not required performed an unchecked net_buf_add_mem(frame_buf, pkt_buf->data, pkt_buf->len). The only guard was __ASSERT_NO_MSG() inside net_buf_simple_add(), which is compiled out without CONFIG_ASSERT, so an oversized packet silently overran the frame buffer.\n\nThe defect is not reachable from the radio: for NET_AF_INET6 packets ieee802154_6lo_encode_pkt() compares the whole packet length against IEEE802154_MTU and takes the fragmentation path when it does not fit, so every buffer copied on the unfragmented branch is within bounds. It is reachable through NET_AF_PACKET sockets bound to an 802.15.4 interface: for NET_SOCK_RAW the 6LoWPAN block is skipped entirely and for NET_SOCK_DGRAM it returns early on the address-family test, leaving no length validation anywhere on the transmit path (net_context_sendto() and net_if_tx() apply none, and pkt_buffer_length() does not clamp the allocation for this L2).\n\nAn application — or, in a CONFIG_USERSPACE build, an unprivileged application thread using the zsock_socket()/zsock_sendto() syscalls — can therefore drive a supervisor-mode out-of-bounds write of chosen bytes past the 125-byte pool buffer. With the default CONFIG_NET_BUF_FIXED_DATA_SIZE of 128 bytes the overrun is bounded to roughly ll_hdr_len + 3 bytes; with CONFIG_NET_BUF_VARIABLE_DATA_SIZE a single storage buffer can be as large as CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE, making the overrun far larger. The consequence is corruption of memory adjacent to the pool, with a crash or further compromise of kernel state as the practical impact.\n\nThe fix validates ll_hdr_len + net_pkt_get_len(pkt) + authtag_len against IEEE802154_MTU before any copy and adds a tailroom-checking copy_pkt_to_frame() helper that returns -EMSGSIZE instead of overrunning the buffer. The same change also linearizes the whole net_buf chain into one MAC frame, so packet storage boundaries no longer become frame boundaries on the wire.","categories":["Unclassified"],"product":"zephyr","vendor":"zephyrproject","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-18415","source_modified_at":"2026-09-30T15:28:20.759Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"zephyr","vendor":"zephyrproject","versions":[{"lessThan":"4.4.2","status":"affected","version":"3.2.0","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"GitHub Advisory Database","source_url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-j76j-jrjc-xgvp","source_modified_at":"2026-09-28T18:49:02Z","fetched_at":"2026-10-23T18:55:00.935475Z","package":{"ecosystem":"other","name":"zephyr"},"range":">= 3.2.0, < 4.4.2"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-18415","source_modified_at":"2026-09-30T15:28:20.759Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"zephyr","ecosystem":null},"version":"4.4.2","basis":"first unaffected version stated in the CVE record"},{"source":"GitHub Advisory Database","source_url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-j76j-jrjc-xgvp","source_modified_at":"2026-09-28T18:49:02Z","fetched_at":"2026-10-23T18:55:00.935475Z","package":{"ecosystem":"other","name":"zephyr"},"version":"4.4.2"}],"cvss":6.3,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00095,"percentile":0.00633,"score_date":"2026-10-23"},"published_at":"2026-09-28T20:00:01.312Z","modified_at":"2026-09-30T15:28:20.759Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-18415","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-09-30T15:28:20.759Z"},{"source":"GitHub Advisory Database","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-j76j-jrjc-xgvp","fetched_at":"2026-10-23T18:55:00.935475Z","source_modified_at":"2026-09-28T18:49:02Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-18415","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","GitHub Advisory Database","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/zephyrproject-rtos/zephyr/commit/3d4c6177d2dbd77d12d9b14cd75a00cdbd826227","tags":["patch"]},{"source":"CVE List","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-j76j-jrjc-xgvp"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"partial","assessed_at":"2026-09-30T15:18:58.650860Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-09-30T15:28:20.759Z","content_hash":"15a542aed9be06c3d4d900e72d4fa286ee8e5247d1fd71995a204d42b352206d"}}