Is CVE-2026-10655 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-10655 being exploited in the wild.

How severe is CVE-2026-10655?

Medium severity, with a CVSS score of 6.5, published 30 June 2026.

Which products and versions are affected?

Zephyr Project Zephyr 4.2.0 to 4.4.0.

Is there a fix for CVE-2026-10655?

A patch was published on 2026-05-01: Fix commit ef47bdf authored Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-10655 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2026-10655?

Check whether you run Zephyr Project Zephyr at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-10655: Zephyr RTOS use-after-free in SNTP asynchronous client

CVE-2026-10655 · Severity: medium · CVSS 6.5 · Published 2026-06-30

Zephyr is an open-source operating system designed for resource-constrained IoT devices. A flaw in its time-synchronization client (SNTP) could allow a remote attacker to crash a device by interfering with network timing responses. This could lead to a denial-of-service state or unpredictable behavior in connected industrial or consumer hardware.

Technologies: Zephyr Project Zephyr. Vendors: Zephyr Project.

Quick answers

Is CVE-2026-10655 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-10655 being exploited in the wild.
How severe is CVE-2026-10655?: Medium severity, with a CVSS score of 6.5, published 30 June 2026.
Which products and versions are affected?: Zephyr Project Zephyr 4.2.0 to 4.4.0.
Is there a fix for CVE-2026-10655?: A patch was published on 2026-05-01: Fix commit ef47bdf authored Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-10655 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2026-10655?: Check whether you run Zephyr Project Zephyr at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A use-after-free vulnerability exists in the Zephyr SNTP client (subsys/net/lib/sntp/sntp.c) due to a lack of synchronization between the calling thread and the socket-service poll thread. When 'sntp_close_async' is invoked (typically during a timeout), it closes the UDP socket file descriptor and frees the underlying 'net_context' while the socket service thread may still be polling it. Because 'net_context' objects are allocated from a fixed pool and reused, this leads to object confusion or a kernel crash. An off-path attacker can trigger this race by dropping or delaying SNTP responses. The issue is resolved by deferring the socket close operation to the socket service thread itself.

Affected products

zephyrproject zephyr 4.2.0 to 4.4.0

Timeline

2026-06-30: advisory: GHSA-34wr-cg29-c4mw published
2026-06-30: disclosed
2026-05-01: patched: Fix commit ef47bdf authored

References

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