{"id":"CVE-2026-14697","aliases":["EUVD-2026-68744","GHSA-x956-p489-8mf5"],"status":"published","title":"IPv6 Neighbor Solicitation packet leak causes TX pool exhaustion denial of service","description":"net_ipv6_send_ns() in subsys/net/ip/ipv6_nbr.c allocates a transmit net_pkt for a Neighbor Solicitation. When it is called with a data packet pending on an unresolved neighbor and that neighbor's pending_queue is already non-empty (an NS is already outstanding), the function appends the data packet and returns early without ever sending the NS via net_send_data() or releasing it with net_pkt_unref(). The freshly allocated NS net_pkt and its attached TX buffers are held only by a local variable and are leaked permanently, never returning to CONFIG_NET_PKT_TX_COUNT / CONFIG_NET_BUF_TX_COUNT.\n\nThe leaking branch sits on the normal IPv6 transmit path: net_ipv6_prepare_for_send() (called from net_if.c) invokes net_ipv6_send_ns() for any outbound or forwarded IPv6 packet whose next hop is not yet in the neighbor cache. An on-link (adjacent) attacker can drive it deterministically by sending a burst of request packets (for example ICMPv6 echo requests or UDP datagrams) that all spoof a single non-existent on-link source address: the node generates a reply to each, the first reply queues an NS, and every subsequent reply during the roughly three-second INCOMPLETE resolution window takes the leaking branch and loses one TX packet. Router-configured nodes forwarding attacker traffic toward a non-existent on-link host leak identically.\n\nBecause the leaked packets are never reclaimed and CONFIG_NET_PKT_TX_COUNT defaults to only 4 (14 for Ethernet), a brief low-rate burst exhausts the TX pool. Once exhausted the node can no longer allocate any transmit packet and cannot send TCP/UDP, ARP/ND, or any reply at all, producing a complete and persistent network denial of service that does not self-heal until reboot. The fix releases the unsent NS packet with net_pkt_unref(pkt) before the early return.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00285,"percentile":0.21185,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-401"],"published":"2026-08-31T19:34:49Z","modified":"2026-11-04T05:00:06Z","products":[{"vendor":"zephyrproject","product":"zephyr"},{"vendor":"zephyrproject-rtos","product":"zephyr"}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/ab2670e8b5b8fcde4a699dd5cbe452abbd233289","tags":["patch","fix"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-x956-p489-8mf5","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/14xxx/CVE-2026-14697.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-14697","tags":["advisory"]},{"url":"https://github.com/zephyrproject-rtos/zephyr","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-14697","title":"IPv6 Neighbor Solicitation packet leak causes TX pool exhaustion denial of service","description":"net_ipv6_send_ns() in subsys/net/ip/ipv6_nbr.c allocates a transmit net_pkt for a Neighbor Solicitation. When it is called with a data packet pending on an unresolved neighbor and that neighbor's pending_queue is already non-empty (an NS is already outstanding), the function appends the data packet and returns early without ever sending the NS via net_send_data() or releasing it with net_pkt_unref(). The freshly allocated NS net_pkt and its attached TX buffers are held only by a local variable and are leaked permanently, never returning to CONFIG_NET_PKT_TX_COUNT / CONFIG_NET_BUF_TX_COUNT.\n\nThe leaking branch sits on the normal IPv6 transmit path: net_ipv6_prepare_for_send() (called from net_if.c) invokes net_ipv6_send_ns() for any outbound or forwarded IPv6 packet whose next hop is not yet in the neighbor cache. An on-link (adjacent) attacker can drive it deterministically by sending a burst of request packets (for example ICMPv6 echo requests or UDP datagrams) that all spoof a single non-existent on-link source address: the node generates a reply to each, the first reply queues an NS, and every subsequent reply during the roughly three-second INCOMPLETE resolution window takes the leaking branch and loses one TX packet. Router-configured nodes forwarding attacker traffic toward a non-existent on-link host leak identically.\n\nBecause the leaked packets are never reclaimed and CONFIG_NET_PKT_TX_COUNT defaults to only 4 (14 for Ethernet), a brief low-rate burst exhausts the TX pool. Once exhausted the node can no longer allocate any transmit packet and cannot send TCP/UDP, ARP/ND, or any reply at all, producing a complete and persistent network denial of service that does not self-heal until reboot. The fix releases the unsent NS packet with net_pkt_unref(pkt) before the early return.","status":"published","published":"2026-08-31T19:34:49.586Z","modified":"2026-11-04T05:00:06.805Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-401"],"updated_at":"2026-11-04T05:21:48.223566Z"}],"euvd":[{"id":"EUVD-2026-68744","description":"net_ipv6_send_ns() in subsys/net/ip/ipv6_nbr.c allocates a transmit net_pkt for a Neighbor Solicitation. When it is called with a data packet pending on an unresolved neighbor and that neighbor's pending_queue is already non-empty (an NS is already outstanding), the function appends the data packet and returns early without ever sending the NS via net_send_data() or releasing it with net_pkt_unref(). The freshly allocated NS net_pkt and its attached TX buffers are held only by a local variable and are leaked permanently, never returning to CONFIG_NET_PKT_TX_COUNT / CONFIG_NET_BUF_TX_COUNT.\n\nThe leaking branch sits on the normal IPv6 transmit path: net_ipv6_prepare_for_send() (called from net_if.c) invokes net_ipv6_send_ns() for any outbound or forwarded IPv6 packet whose next hop is not yet in the neighbor cache. An on-link (adjacent) attacker can drive it deterministically by sending a burst of request packets (for example ICMPv6 echo requests or UDP datagrams) that all spoof a single non-existent on-link source address: the node generates a reply to each, the first reply queues an NS, and every subsequent reply during the roughly three-second INCOMPLETE resolution window takes the leaking branch and loses one TX packet. Router-configured nodes forwarding attacker traffic toward a non-existent on-link host leak identically.\n\nBecause the leaked packets are never reclaimed and CONFIG_NET_PKT_TX_COUNT defaults to only 4 (14 for Ethernet), a brief low-rate burst exhausts the TX pool. Once exhausted the node can no longer allocate any transmit packet and cannot send TCP/UDP, ARP/ND, or any reply at all, producing a complete and persistent network denial of service that does not self-heal until reboot. The fix releases the unsent NS packet with net_pkt_unref(pkt) before the early return.","status":"published","published":"2026-08-31T19:34:49Z","modified":"2026-11-04T05:00:06Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-04T07:00:56.720215Z"}],"nvd":[{"id":"CVE-2026-14697","description":"net_ipv6_send_ns() in subsys/net/ip/ipv6_nbr.c allocates a transmit net_pkt for a Neighbor Solicitation. When it is called with a data packet pending on an unresolved neighbor and that neighbor's pending_queue is already non-empty (an NS is already outstanding), the function appends the data packet and returns early without ever sending the NS via net_send_data() or releasing it with net_pkt_unref(). The freshly allocated NS net_pkt and its attached TX buffers are held only by a local variable and are leaked permanently, never returning to CONFIG_NET_PKT_TX_COUNT / CONFIG_NET_BUF_TX_COUNT.\n\nThe leaking branch sits on the normal IPv6 transmit path: net_ipv6_prepare_for_send() (called from net_if.c) invokes net_ipv6_send_ns() for any outbound or forwarded IPv6 packet whose next hop is not yet in the neighbor cache. An on-link (adjacent) attacker can drive it deterministically by sending a burst of request packets (for example ICMPv6 echo requests or UDP datagrams) that all spoof a single non-existent on-link source address: the node generates a reply to each, the first reply queues an NS, and every subsequent reply during the roughly three-second INCOMPLETE resolution window takes the leaking branch and loses one TX packet. Router-configured nodes forwarding attacker traffic toward a non-existent on-link host leak identically.\n\nBecause the leaked packets are never reclaimed and CONFIG_NET_PKT_TX_COUNT defaults to only 4 (14 for Ethernet), a brief low-rate burst exhausts the TX pool. Once exhausted the node can no longer allocate any transmit packet and cannot send TCP/UDP, ARP/ND, or any reply at all, producing a complete and persistent network denial of service that does not self-heal until reboot. The fix releases the unsent NS packet with net_pkt_unref(pkt) before the early return.","status":"published","published":"2026-08-31T20:17:03.253Z","modified":"2026-11-04T05:18:43.373Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-401"],"updated_at":"2026-11-04T06:53:20.502063Z"}],"osv":[{"id":"CVE-2026-14697","title":"IPv6 Neighbor Solicitation packet leak causes TX pool exhaustion denial of service","description":"net_ipv6_send_ns() in subsys/net/ip/ipv6_nbr.c allocates a transmit net_pkt for a Neighbor Solicitation. When it is called with a data packet pending on an unresolved neighbor and that neighbor's pending_queue is already non-empty (an NS is already outstanding), the function appends the data packet and returns early without ever sending the NS via net_send_data() or releasing it with net_pkt_unref(). The freshly allocated NS net_pkt and its attached TX buffers are held only by a local variable and are leaked permanently, never returning to CONFIG_NET_PKT_TX_COUNT / CONFIG_NET_BUF_TX_COUNT.\n\nThe leaking branch sits on the normal IPv6 transmit path: net_ipv6_prepare_for_send() (called from net_if.c) invokes net_ipv6_send_ns() for any outbound or forwarded IPv6 packet whose next hop is not yet in the neighbor cache. An on-link (adjacent) attacker can drive it deterministically by sending a burst of request packets (for example ICMPv6 echo requests or UDP datagrams) that all spoof a single non-existent on-link source address: the node generates a reply to each, the first reply queues an NS, and every subsequent reply during the roughly three-second INCOMPLETE resolution window takes the leaking branch and loses one TX packet. Router-configured nodes forwarding attacker traffic toward a non-existent on-link host leak identically.\n\nBecause the leaked packets are never reclaimed and CONFIG_NET_PKT_TX_COUNT defaults to only 4 (14 for Ethernet), a brief low-rate burst exhausts the TX pool. Once exhausted the node can no longer allocate any transmit packet and cannot send TCP/UDP, ARP/ND, or any reply at all, producing a complete and persistent network denial of service that does not self-heal until reboot. The fix releases the unsent NS packet with net_pkt_unref(pkt) before the early return.","status":"published","published":"2026-08-31T19:34:49.586Z","modified":"2026-11-05T03:31:26.443860842Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-401"],"updated_at":"2026-11-05T07:12:28.867005Z"}]}}