{"id":"CVE-2026-10640","title":"Use-after-free reading `net_pkt` `iface` after send in IPv6 Neighbor Discovery (`ipv6_nbr.c`)","summary":"Zephyr's IPv6 Neighbor Discovery send paths (net_ipv6_send_na, net_ipv6_send_ns, net_ipv6_send_rs in subsys/net/ip/ipv6_nbr.c) updated the per-interface ICMP-sent statistics by calling net_pkt_iface(pkt) after net_send_data(pkt) had alre…","severity":"medium","cvss":4.2,"cvssVector":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L","cvssSource":"cna","cwe":["CWE-416"],"vendor":"zephyrproject","product":"zephyr","affected":["zephyr >= 3.3.0 < 4.3.1","zephyr >= 4.4.0 < 4.4.1"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-06-16T15:28:30.797017Z"},"published":"2026-06-16","updated":"2026-10-15","sourceUpdated":"2026-10-15T22:10:02.544Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-10640","references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/aaed8332a62b0490a2f3c2cbabe272f575068eaa","label":"Fix commit"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-r74c-mr4m-7g9g","label":"GHSA-r74c-mr4m-7g9g"}],"tags":["cve.org"],"epss":0.0037,"epssPercentile":0.29271,"ingestedAt":"2026-10-15T22:48:25.563Z","slug":"CVE-2026-10640","body":"## Overview\n\nZephyr's IPv6 Neighbor Discovery send paths (net_ipv6_send_na, net_ipv6_send_ns, net_ipv6_send_rs in subsys/net/ip/ipv6_nbr.c) updated the per-interface ICMP-sent statistics by calling net_pkt_iface(pkt) after net_send_data(pkt) had already returned successfully. On the success path the network stack owns and releases the packet's reference (the L2/driver send unrefs it, e.g. ethernet_send -> net_pkt_unref), so for a freshly allocated packet with refcount 1 the net_pkt slab block can be freed before the statistics line runs (synchronously when no TX queue thread is configured, or via a concurrent TX thread otherwise).\n\nThe subsequent net_pkt_iface(pkt) reads pkt->iface from the freed slab block, and with CONFIG_NET_STATISTICS_PER_INTERFACE enabled that loaded pointer is dereferenced to increment iface->stats.icmp.sent, a use-after-free (CWE-416). If the slab block was reallocated in the meantime the read/increment targets unrelated or attacker-influenced memory, yielding corrupted statistics, a fault/crash (denial of service), or potential limited memory corruption.\n\nThe vulnerable Neighbor Advertisement path is reachable by any unauthenticated on-link node simply by sending ICMPv6 Neighbor Solicitations to a Zephyr node with native IPv6 enabled (handle_ns_input -> net_ipv6_send_na).\n\nAffected from v3.3.0 through v4.4.0; the fix uses the already-available iface argument instead of touching the sent packet. Configurations without per-interface statistics dereference only a global counter and are not affected by the memory-safety aspect.\n\n## Affected\n\n- `zephyr >= 3.3.0 < 4.3.1`\n- `zephyr >= 4.4.0 < 4.4.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":23,"depthScoreParts":{"impact":23.1,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}