CVE-2026-14366: zephyr Use After Free (CVSS 6.4)

Description

The Silicon Labs SiWx917 WiFi driver's transmit callback siwx91x_send() in drivers/wifi/siwx91x/siwx91x_wifi.c frees a network packet it does not own. In the Zephyr TX path the net_pkt is owned by the L2/networking stack; the driver only borrows it to copy the frame bytes into a local net_buf. Before the fix, after transmitting, siwx91x_send() additionally called net_pkt_unref(pkt) on the caller-owned packet, dropping its last reference and returning it to the shared packet pool prematurely. This code path is compiled in by default (CONFIG_WIFI_SILABS_SIWX91X_NET_STACK_NATIVE). The caller, ethernet_send() in subsys/net/l2/ethernet/ethernet.c, keeps using the packet after the driver returns: it reads net_pkt_get_len(pkt), updates TX statistics, and then performs its own net_pkt_unref(pkt). Because the driver already released the packet, these are use-after-free reads followed by a second unref (a double free). When concurrent network activity recycles the freed slab slot between the two unrefs, the trailing unref decrements a different, live packet's reference count and frees it, corrupting the net_pkt pool shared by both the receive and transmit paths. The defect is exercised by ordinary transmission over the native-stack SiWx917 WiFi interface, and an adjacent attacker on the same WiFi network can induce transmissions (for example ARP or ICMP echo replies, or TCP handshakes) to drive the path. The primary observable impact is loss of availability (transmit hangs and crashes from pool corruption), with race-dependent memory corruption of the kernel networking buffer pool. The fix removes the erroneous net_pkt_unref(pkt) from siwx91x_send(); the driver's receive-path unref, which correctly frees a packet the driver itself allocated, is unaffected.

Metrics

CVSS 3.1

6.4/10

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

EPSS Probability

0.16%

5.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-416

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
zephyrproject	zephyr	>= 4.1.0, < 4.4.2

References

Timeline

Published: Aug 31, 2026
Last Modified: Sep 1, 2026
Status: Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-14366?

The Silicon Labs SiWx917 WiFi driver's transmit callback siwx91x_send() in drivers/wifi/siwx91x/siwx91x_wifi.c frees a network packet it does not own. In the Zephyr TX path the net_pkt is owned by the L2/networking stack; the driver only borrows it to copy the frame bytes into a local net_buf. Before the fix, after transmitting, siwx91x_send() additionally called net_pkt_unref(pkt) on the caller-owned packet, dropping its last reference and returning it to the shared packet pool prematurely. This code path is compiled in by default (CONFIG_WIFI_SILABS_SIWX91X_NET_STACK_NATIVE). The caller, ethernet_send() in subsys/net/l2/ethernet/ethernet.c, keeps using the packet after the driver returns: it reads net_pkt_get_len(pkt), updates TX statistics, and then performs its own net_pkt_unref(pkt). Because the driver already released the packet, these are use-after-free reads followed by a second unref (a double free). When concurrent network activity recycles the freed slab slot between the two unrefs, the trailing unref decrements a different, live packet's reference count and frees it, corrupting the net_pkt pool shared by both the receive and transmit paths. The defect is exercised by ordinary transmission over the native-stack SiWx917 WiFi interface, and an adjacent attacker on the same WiFi network can induce transmissions (for example ARP or ICMP echo replies, or TCP handshakes) to drive the path. The primary observable impact is loss of availability (transmit hangs and crashes from pool corruption), with race-dependent memory corruption of the kernel networking buffer pool. The fix removes the erroneous net_pkt_unref(pkt) from siwx91x_send(); the driver's receive-path unref, which correctly frees a packet the driver itself allocated, is unaffected.

How severe is CVE-2026-14366?

CVE-2026-14366 has a CVSS score of 6.4/10 (MEDIUM severity). The EPSS model estimates a 0.16% probability of exploitation in the next 30 days.

How do I fix CVE-2026-14366?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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