What is the CVSS score of EUVD-2026-37117?

EUVD-2026-37117 has a CVSS 3.1 base score of 7.1 (High). CVSS vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H. EPSS exploitation probability: 0.1%.

Which versions of Zephyr RTOS are affected by EUVD-2026-37117?

Zephyr RTOS-based IoT and edge devices (versions 3.3.0-4.4.0) face potential denial of service from any attacker on the local network segment, impacting device uptime and service continuity.. A patch is available.

How to fix or mitigate EUVD-2026-37117?

Within 24 hours: inventory all Zephyr RTOS deployments (versions 3.3.0-4.4.0), determine which have CONFIG_NET_STATISTICS_PER_INTERFACE enabled, and segment affected devices from untrusted networks where feasible. Within 7 days: obtain vendor patch, test in non-production environment, and begin staged rollout to production systems. Within 30 days: complete patch deployment to all affected instances and validate remediations through post-patch testing.

Zephyr RTOS EUVD-2026-37117

| CVE-2026-10640 HIGH

Use After Free (CWE-416)

2026-06-16 zephyr

Denial Of Service Use After Free Memory Corruption Buffer Overflow Zephyr

7.1

CVSS 3.1 · NVD

Severity by source

Vendor (zephyr) PRIMARY

MEDIUM

qualitative

NVD

7.1 HIGH

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

vuln.today AI

7.1 HIGH

On-link unauthenticated trigger via ICMPv6 (AV:A/PR:N/UI:N); primary impact is crash/DoS (A:H) with only marginal integrity from stat corruption (I:L) and no confidentiality (C:N).

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

4.0 AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (zephyr).

CVSS VectorNVD

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

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

High

Lifecycle Timeline

Analysis Updated

Jun 26, 2026 - 20:58 vuln.today

v3 (cvss_changed)

Analysis Updated

Jun 26, 2026 - 20:58 vuln.today

v2 (cvss_changed)

Re-analysis Queued

Jun 26, 2026 - 20:52 vuln.today

cvss_changed

Severity Changed

Jun 26, 2026 - 20:52 NVD

MEDIUM HIGH

CVSS changed

Jun 26, 2026 - 20:52 NVD

4.2 (MEDIUM) 7.1 (HIGH)

Source Code Evidence Fetched

Jun 16, 2026 - 15:41 vuln.today

Analysis Generated

Jun 16, 2026 - 15:41 vuln.today

DescriptionNVD

Zephyr's IPv6 Neighbor Discovery send paths (net_ipv6_send_na, net_ipv6_send_ns, net_ipv6_send_rs in subsys/net/ip/ipv6_nbr.c) updated the per-interface ICMP-sent statistics by calling net_pkt_iface(pkt) after net_send_data(pkt) had already returned successfully. On the success path the network stack owns and releases the packet's reference (the L2/driver send unrefs it, e.g. ethernet_send - net_pkt_unref), so for a freshly allocated packet with refcount 1 the net_pkt slab block can be freed before the statistics line runs (synchronously when no TX queue thread is configured, or via a concurrent TX thread otherwise).

The subsequent net_pkt_iface(pkt) reads pkt-iface from the freed slab block, and with CONFIG_NET_STATISTICS_PER_INTERFACE enabled that loaded pointer is dereferenced to increment iface-stats.icmp.sent, a use-after-free (CWE-416). If the slab block was reallocated in the meantime the read/increment targets unrelated or attacker-influenced memory, yielding corrupted statistics, a fault/crash (denial of service), or potential limited memory corruption.

The vulnerable Neighbor Advertisement path is reachable by any unauthenticated on-link node simply by sending ICMPv6 Neighbor Solicitations to a Zephyr node with native IPv6 enabled (handle_ns_input - net_ipv6_send_na).

Affected from v3.3.0 through v4.4.0; the fix uses the already-available iface argument instead of touching the sent packet. Configurations without per-interface statistics dereference only a global counter and are not affected by the memory-safety aspect.

AnalysisAI

Denial of service (and potential limited memory corruption) in the Zephyr RTOS IPv6 networking stack (versions 3.3.0 through 4.4.0) stems from a use-after-free in the IPv6 Neighbor Discovery send paths, where per-interface ICMP statistics are updated by reading from a network packet after the stack has already freed it. Any unauthenticated on-link node can trigger the Neighbor Advertisement path simply by sending ICMPv6 Neighbor Solicitations to a Zephyr node with native IPv6 and CONFIG_NET_STATISTICS_PER_INTERFACE enabled, causing a freed slab block to be dereferenced. There is no public exploit identified at time of analysis and EPSS is low (0.14%, 4th percentile); a vendor patch is available, and impact is largely limited to crashes/DoS with only theoretical limited memory corruption.

Technical ContextAI

The affected component is Zephyr's IPv6 Neighbor Discovery implementation in subsys/net/ip/ipv6_nbr.c, specifically net_ipv6_send_na, net_ipv6_send_ns, and net_ipv6_send_rs. Zephyr manages network packets (net_pkt) using reference-counted slab-allocated blocks; on a successful net_send_data() call, the L2/driver send path (e.g. ethernet_send) owns and releases the packet's final reference via net_pkt_unref, freeing the slab block. The root cause (CWE-416, Use After Free) is that the statistics line called net_pkt_iface(pkt) after net_send_data() returned, reading the pkt->iface field from a slab block whose refcount may already have dropped to zero and been freed - synchronously when no dedicated TX queue thread is configured, or via a race with a concurrent TX thread otherwise. When CONFIG_NET_STATISTICS_PER_INTERFACE is enabled, that stale pointer is dereferenced to increment iface->stats.icmp.sent. The CPE cpe:2.3:a:zephyrproject:zephyr identifies the affected product. The fix is trivial and correct: use the already-available iface function argument instead of re-deriving it from the sent packet.

RemediationAI

Upgrade to Zephyr 4.5.0 or later, which incorporates the upstream fix (commit aaed8332a62b0490a2f3c2cbabe272f575068eaa) that replaces net_pkt_iface(pkt) with the already-available iface argument in net_ipv6_send_na, net_ipv6_send_ns, and net_ipv6_send_rs; see the advisory at https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-r74c-mr4m-7g9g. Because Zephyr is typically vendored into device firmware, downstream maintainers should cherry-pick the one-line-per-function commit into their pinned tree and rebuild/redeploy firmware. As a compensating control where firmware cannot be rebuilt immediately, disabling CONFIG_NET_STATISTICS_PER_INTERFACE removes the memory-safety impact (the global-counter path is not affected), at the cost of losing per-interface ICMP statistics; alternatively, restricting or filtering inbound ICMPv6 Neighbor Solicitations at the L2 segment or disabling native IPv6 where unused reduces reachability, with the trade-off of impaired IPv6 neighbor discovery functionality.