CVE-2026-10638: subsys/net/ip/icmpv6.c reads the network interface from a net_pkt after that packet has been handed to net_try

Q: How do I fix CVE-2026-10638?

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

Q: Is CVE-2026-10638 being exploited?

CVE-2026-10638 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-2026-10638 affect?

CVE-2026-10638 affects zephyr. Severity is medium (CVSS 5.9). subsys/net/ip/icmpv6.c reads the network interface from a net_pkt after that packet has been handed to net_try_send_data(). In icmpv6_handle_echo_request() and net_icmpv6_send_error(), the post-send statistics update calls net_pkt_iface(rep

Q: How urgent is CVE-2026-10638?

Priority 33/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.9REMOTEUPGRADE

CVE-2026-10638 is a medium-severity flaw (CVSS 5.9) affecting zephyr. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

subsys/net/ip/icmpv6.c reads the network interface from a net_pkt after that packet has been handed to net_try_send_data(). In icmpv6_handle_echo_request() and net_icmpv6_send_error(), the post-send statistics update calls net_pkt_iface(reply)/net_pkt_iface(pkt) on the just-sent packet. The send path (net_try_send_data -> net_if_tx) unreferences and may free the packet back to its memory slab before returning — synchronously in the RX thread whe

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 71%)
CISA exploited list	No
Weakness	CWE-416
Published	2026-06-16
Last modified	2026-10-26

Publisher (CNA): Zephyr Project · Vendor: zephyrproject

Last updated 2026-10-26 · 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
2026-10-26 12:10 UTCUpdated Record last modified

zephyrproject zephyr UPGRADE

Affected: >= 4.2.0 and < 4.5.0

Fixed in: 4.5.0

Safe to downgrade to: a release before 4.2.0

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-2026-10638?

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

Is CVE-2026-10638 being exploited?

CVE-2026-10638 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-2026-10638 affect?

CVE-2026-10638 affects zephyr. Severity is medium (CVSS 5.9). subsys/net/ip/icmpv6.c reads the network interface from a net_pkt after that packet has been handed to net_try_send_data(). In icmpv6_handle_echo_request() and net_icmpv6_send_error(), the post-send statistics update calls net_pkt_iface(rep

How urgent is CVE-2026-10638?

Priority 33/100. Remotely exploitable, no login, no user action

Related CVEs

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CVE-2026-10641 HIGH 7.1 UPGRADE Zephyr's Bluetooth Classic Hands-Free Profile (HFP) Hands-Free role parser (subsys/bluetooth/host/classic/hfp_
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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
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References

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