CVE-2026-10639: In Zephyr's native IPv4 stack, icmpv4_handle_echo_request() in subsys/net/ip/icmpv4.c builds an echo-reply pac

Q: How do I fix CVE-2026-10639?

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

Q: Is CVE-2026-10639 being exploited?

CVE-2026-10639 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-2026-10639 affect?

CVE-2026-10639 affects zephyr. Severity is medium (CVSS 4.8). In Zephyr's native IPv4 stack, icmpv4_handle_echo_request() in subsys/net/ip/icmpv4.c builds an echo-reply packet (reply), hands it to net_try_send_data(), and then, on success, calls net_stats_update_icmp_sent(net_pkt_iface(reply)). net_tr

Q: How urgent is CVE-2026-10639?

Priority 30/100. Public exploit reference; Remotely exploitable, no login, no user action

This week

MEDIUM 4.8REMOTEUPGRADE

CVE-2026-10639 is a medium-severity flaw (CVSS 4.8) affecting zephyr. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Zephyr's native IPv4 stack, icmpv4_handle_echo_request() in subsys/net/ip/icmpv4.c builds an echo-reply packet (reply), hands it to net_try_send_data(), and then, on success, calls net_stats_update_icmp_sent(net_pkt_iface(reply)). net_try_send_data() transfers ownership of reply to the TX path (net_if_try_queue_tx -> net_if_tx -> L2/driver send, or the asynchronous net_if_tx_thread), which can unref it to refcount 0 and return the struct net_p

Why this priority

Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	4.8 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 86%)
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: >= 1.14.0 and < 4.5.0

Fixed in: 4.5.0

Safe to downgrade to: a release before 1.14.0

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-2026-10639?

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

Is CVE-2026-10639 being exploited?

CVE-2026-10639 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-2026-10639 affect?

CVE-2026-10639 affects zephyr. Severity is medium (CVSS 4.8). In Zephyr's native IPv4 stack, icmpv4_handle_echo_request() in subsys/net/ip/icmpv4.c builds an echo-reply packet (reply), hands it to net_try_send_data(), and then, on success, calls net_stats_update_icmp_sent(net_pkt_iface(reply)). net_tr

How urgent is CVE-2026-10639?

Priority 30/100. Public exploit reference; Remotely exploitable, no login, no user action

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References

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