{"id":"CVE-2026-10637","title":"Use-after-free of `net_pkt` in IPv6 MLD send path triggerable by a link-local MLD Query","summary":"subsys/net/ip/ipv6_mld.c:mld_send() read the packet interface via net_pkt_iface(pkt) after net_send_data(pkt) returned successfully. Per the network stack's ownership contract (include/zephyr/net/net_core.h, and the explicit warning in s…","severity":"medium","cvss":5.9,"cvssVector":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H","cvssSource":"cna","cwe":["CWE-416"],"vendor":"zephyrproject","product":"zephyr","affected":["zephyr >= 1.12.0 < 4.3.1","zephyr >= 4.4.0 < 4.4.1"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-06-16T15:30:13.376607Z"},"published":"2026-06-16","updated":"2026-10-15","sourceUpdated":"2026-10-15T22:10:01.063Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-10637","references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/3159c53e8e7d233c2a85a0798cf25ac441db6dae","label":"Fix commit"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-m23w-34pp-4h92","label":"GHSA-m23w-34pp-4h92"}],"tags":["cve.org"],"epss":0.00299,"epssPercentile":0.21045,"ingestedAt":"2026-10-15T22:48:25.564Z","slug":"CVE-2026-10637","body":"## Overview\n\nsubsys/net/ip/ipv6_mld.c:mld_send() read the packet interface via net_pkt_iface(pkt) after net_send_data(pkt) returned successfully. Per the network stack's ownership contract (include/zephyr/net/net_core.h, and the explicit warning in subsys/net/ip/net_core.c:453-460 'do not use pkt after that call'), a successful send transfers ownership of the net_pkt and the L2 driver frees it (e.g. ethernet_send() unrefs the packet on success, subsys/net/l2/ethernet/ethernet.c:790), returning it to its k_mem_slab.\n\nThe subsequent net_pkt_iface(pkt) is therefore a read of a freed object; the recovered interface pointer is then dereferenced and incremented by the per-interface statistics path (net_stats.h UPDATE_STAT/SET_STAT) when CONFIG_NET_STATISTICS_PER_INTERFACE is enabled. If the freed slot is concurrently reallocated, pkt->iface may read back as NULL (NULL-pointer dereference / crash) or as a stale/garbage pointer (stray increment write / memory corruption).\n\nThe path is reachable remotely on the local link without authentication: handle_mld_query() (registered for NET_ICMPV6_MLD_QUERY) responds to a valid MLDv2 General Query (unspecified multicast address, hop limit 1) by calling send_mld_report() -> mld_send().\n\nThe result is a remotely triggerable denial of service of the networking stack, with a narrow possibility of memory corruption. The fix caches the interface in a local before sending and no longer touches the packet after net_send_data(). The IPv4/IGMP sibling (igmp_send) already used the corrected pattern.\n\n## Affected\n\n- `zephyr >= 1.12.0 < 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":33,"depthScoreParts":{"impact":32.5,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}