# CVE-2026-10666 — zephyrproject zephyr

> As of 2026-07-13, CVE-2026-10666 is a HIGH-severity vulnerability in zephyrproject zephyr, CVSS v3.1 8.1, EPSS 0.3% (26.7th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-10666 as of 2026-07-13; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-07-13

## What is CVE-2026-10666?

parse_ipv4() in subsys/net/ip/utils.c (reached via net_ipaddr_parse() for strings of the form "a.b.c.d:port") copies the port substring into a fixed 17-byte stack buffer (char ipaddr[NET_IPV4_ADDR_LEN + 1]) using a length of str_len - end - 1, where str_len is the full, unbounded input length and end is only the (<=15-byte) offset of the ':' delimiter. Because the destination size is never consulted, a crafted address string with a long suffix after the colon (e.g. "1.2.3.4:" followed by hundreds of bytes) causes an out-of-bounds stack write whose length and contents are fully attacker-controlled (memcpy of the suffix plus a trailing NUL), enabling memory corruption and at minimum a denial of service, and potentially control-flow hijack. The parser is reached from the standard socket API (zsock_getaddrinfo / literal-address resolution), DNS server-string configuration, and the eswifi Wi-Fi co-processor DNS-response path, so an application that resolves a network-influenced address string is exposed. The bug was introduced when the parser was added (Zephyr v1.9.0) and shipped in all releases through v4.4.0. The fix removes the unbounded copy and validates the port length before copying into a small dedicated buffer. Note: the equivalent IPv6 "[addr]:port" path in parse_ipv6() retains the same unbounded copy at this commit and remains a separate, still-reachable instance of the defect.

The record classifies CVE-2026-10666 under weakness class [CWE-787](https://intel.threadlinqs.com/cwe/CWE-787). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 85 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.1 — HIGH (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **EPSS (FIRST):** 0.3% probability of exploitation in the next 30 days, higher than 26.7% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.1/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-12, last modified 2026-07-13

## Is CVE-2026-10666 being exploited?

It currently carries a trending score of 36 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [zephyrproject](https://intel.threadlinqs.com/vendors/zephyrproject): zephyr

## How to fix CVE-2026-10666

No vendor patch reference has been recorded for CVE-2026-10666 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-10666

No threat campaign in the Threadlinqs corpus currently references CVE-2026-10666, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-07-14. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com — patch](https://github.com/zephyrproject-rtos/zephyr/commit/1c8d19a51f9a3c1be6de53854c8ad8c2720a0f48)
- [github.com — patch (6e119a636a57be449ea21e73cad762ebc6f5ff7a)](https://github.com/zephyrproject-rtos/zephyr/commit/6e119a636a57be449ea21e73cad762ebc6f5ff7a)

**Other references**

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

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-10666
Full detection coverage and IOCs for threats exploiting CVE-2026-10666 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp