IPv6 Neighbor Solicitation packet leak causes TX pool exhaustion denial of service
Summary
| CVE | CVE-2026-14697 |
|---|---|
| State | PUBLISHED |
| Assigner | zephyr |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-31 20:17:03 UTC |
| Updated | 2026-09-01 20:56:59 UTC |
| 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. 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. |
Risk And Classification
Primary CVSS: v3.1 6.5 MEDIUM from [email protected]
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.001750000 probability, percentile 0.070210000 (date 2026-09-03)
Problem Types: CWE-401 | CWE-401 dos
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 6.5 | MEDIUM | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | CNA | CVSS | 6.5 | MEDIUM | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
Attack Vector
AdjacentAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Zephyrproject | Zephyr | affected 4.3.0 4.4.2 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-x956-p489-... | [email protected] | github.com | |
| github.com/zephyrproject-rtos/zephyr/commit/ab2670e8b5b8fcde4a699dd5cbe4... | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.