# CVE-2026-10666: Zephyr OS stack overflow in IPv4 and IPv6 address parsing

Source: https://junglewise.ai/threats/cve-2026-10666-zephyr-os-stack-overflow-in-ipv4-and-ipv6-address-parsing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-12. Updated: 2026-07-12  
License: CC BY 4.0 with a link back

CVE-2026-10666 · Severity: high · CVSS 8.1 · Published 2026-07-12

Zephyr OS, a popular operating system for embedded and IoT devices, contains a flaw in how it processes network addresses. An attacker could send a specially crafted network address containing an excessively long port number to crash the device or potentially take control of it. This affects devices using Zephyr for networking, including those handling DNS or Wi-Fi communications.

Technologies: [Zephyr Project Zephyr OS](https://junglewise.ai/threats/technologies/zephyr-os). Vendors: [Zephyr Project](https://junglewise.ai/threats/vendors/zephyr-project).

## Quick answers

**Is CVE-2026-10666 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-10666 being exploited in the wild.

**How severe is CVE-2026-10666?** High severity, with a CVSS score of 8.1, published 12 July 2026.

**Which products and versions are affected?** Zephyr Project Zephyr OS v1.9.0 to v4.4.0.

**Is there a fix for CVE-2026-10666?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-10666 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-10666?** Check whether you run Zephyr Project Zephyr OS 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 stack-based buffer overflow exists in `parse_ipv4()` and `parse_ipv6()` within `subsys/net/ip/utils.c`. When parsing address strings in the format "a.b.c.d:port" or "[addr]:port", the code copies the port substring into a fixed-size stack buffer (17 bytes for IPv4) using a length derived from the unbounded input string without verifying the destination buffer's limits. This vulnerability is reachable via `net_ipaddr_parse()`, which is used by the standard socket API (`zsock_getaddrinfo`), DNS configuration, and certain Wi-Fi co-processor paths. An attacker can trigger an out-of-bounds write by providing a long suffix after the colon delimiter. Patches have been merged into the main branch and backported to stable releases (v4.4, v4.3, v3.7).

## Affected products

- Zephyr Project Zephyr OS v1.9.0 to v4.4.0

## Timeline

- 2026-07-12: advisory: GHSA-532c-7g7f-jhmh published
- 2026-07-12: disclosed: CVE-2026-10666 published

## References

- [https://github.com/zephyrproject-rtos/zephyr](https://github.com/zephyrproject-rtos/zephyr)
- [https://github.com/zephyrproject-rtos/zephyr/commit/1c8d19a51f9a3c1be6de53854c8ad8c2720a0f48](https://github.com/zephyrproject-rtos/zephyr/commit/1c8d19a51f9a3c1be6de53854c8ad8c2720a0f48)
- [https://github.com/zephyrproject-rtos/zephyr/commit/6e119a636a57be449ea21e73cad762ebc6f5ff7a](https://github.com/zephyrproject-rtos/zephyr/commit/6e119a636a57be449ea21e73cad762ebc6f5ff7a)
- [https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-532c-7g7f-jhmh](https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-532c-7g7f-jhmh)

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