CVE Catalog

CVE-2026-14697

MediumCVSS 6.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.18%

7th percentile - higher than 7% of all known CVEs

Summary

In the IPv6 subsystem of the Zephyr stack (subsys/net/ip/ipv6_nbr.c), the net_ipv6_send_ns() function allocates a transmit net_pkt for a Neighbor Solicitation. When called with a data packet pending on an unresolved neighbor and the neighbor's pending_queue is already non-empty, the function appends the data packet and returns early without 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.

Risk Assessment

An on-link attacker can deterministically trigger the TX packet leak, exhausting the transmit packet pool (default only 4, 14 for Ethernet). Once exhausted, the node cannot send any packets (TCP/UDP, ARP/ND, or any reply), resulting in a complete and persistent denial of service that does not self-heal until reboot.

Recommendation

Apply the fix that releases the unsent NS packet with net_pkt_unref(pkt) before the early return. If the fix is unavailable, restrict trust in the local network and monitor TX packet pool usage.

Other vulnerabilities in Zephyr

See all
Original NVD description (English source)

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. The 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. Because 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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS