{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-18415","assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","state":"PUBLISHED","assignerShortName":"zephyr","dateReserved":"2026-07-30T17:54:11.604Z","datePublished":"2026-09-28T20:00:01.312Z","dateUpdated":"2026-09-30T15:28:20.759Z"},"containers":{"cna":{"providerMetadata":{"orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","shortName":"zephyr","dateUpdated":"2026-09-28T20:00:01.312Z"},"title":"Out-of-bounds write in the IEEE 802.15.4 L2 transmit path for oversized non-6LoWPAN frames","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"zephyrproject","product":"zephyr","collectionURL":"https://github.com/zephyrproject-rtos/zephyr","packageName":"zephyr","defaultStatus":"unaffected","programFiles":["subsys/net/l2/ieee802154/ieee802154.c"],"programRoutines":[{"name":"ieee802154_send"}],"versions":[{"version":"3.2.0","status":"affected","versionType":"semver","lessThan":"4.4.2"}]}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/3d4c6177d2dbd77d12d9b14cd75a00cdbd826227","name":"Fix commit","tags":["patch"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-j76j-jrjc-xgvp","name":"GHSA-j76j-jrjc-xgvp"}],"metrics":[{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H","baseScore":6.3,"baseSeverity":"MEDIUM"}}],"problemTypes":[{"descriptions":[{"lang":"en","description":"bounds","cweId":"CWE-787","type":"CWE"}]}],"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-18415","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-09-30T15:18:58.650860Z"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-09-30T15:28:20.759Z"}}]}}