CVE-2026-10640: Zephyr's IPv6 Neighbor Discovery send paths (net_ipv6_send_na, net_ipv6_send_ns, net_ipv6_send_rs in subsys/ne

Q: How do I fix CVE-2026-10640?

zephyr: upgrade to 4.5.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-10640 being exploited?

CVE-2026-10640 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-10640 affect?

CVE-2026-10640 affects zephyr. Severity is medium (CVSS 4.2). 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

Q: How urgent is CVE-2026-10640?

Priority 27/100. Public exploit reference

Routine

MEDIUM 4.2UPGRADE

CVE-2026-10640 is a medium-severity flaw (CVSS 4.2) affecting zephyr. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	4.2 (Medium)
Attack vector	Adjacent network
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 69%)
CISA exploited list	No
Weakness	CWE-416
Published	2026-06-16
Last modified	2026-10-25

Publisher (CNA): Zephyr Project · Vendor: zephyrproject

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-16 15:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

zephyrproject zephyr UPGRADE

Affected: >= 3.3.0 and < 4.5.0

Fixed in: 4.5.0

Safe to downgrade to: a release before 3.3.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-10640?

zephyr: upgrade to 4.5.0. Exact commands for each OS are on this page.

Is CVE-2026-10640 being exploited?

CVE-2026-10640 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-10640 affect?

CVE-2026-10640 affects zephyr. Severity is medium (CVSS 4.2). 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

How urgent is CVE-2026-10640?

Priority 27/100. Public exploit reference

Related CVEs

CVE-2026-10641 HIGH 7.1 UPGRADE Zephyr's Bluetooth Classic Hands-Free Profile (HFP) Hands-Free role parser (subsys/bluetooth/host/classic/hfp_
CVE-2026-10651 HIGH 7.1 UPGRADE bt_sdp_parse_attribute() in subsys/bluetooth/host/classic/sdp.c validated only that the SDP record buffer held
CVE-2026-10639 MEDIUM 4.8 UPGRADE In Zephyr's native IPv4 stack, icmpv4_handle_echo_request() in subsys/net/ip/icmpv4.c builds an echo-reply pac
CVE-2026-10658 HIGH 7.1 UPGRADE bt_iso_recv() in subsys/bluetooth/host/iso.c pulled the ISO SDU header (4 bytes) or, when the timestamp flag i
CVE-2026-10636 LOW 3.7 UPGRADE In Zephyr's IPv4 IGMP implementation, igmp_send() in subsys/net/ip/igmp.c read the network interface back out

References

← Back to latest CVEs