# CVE-2026-10643: Zephyr RTOS heap overflow in IP socket recvmsg implementation

Source: https://junglewise.ai/threats/cve-2026-10643-zephyr-rtos-heap-overflow-in-ip-socket-recvmsg-implementation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-28. Updated: 2026-06-28  
License: CC BY 4.0 with a link back

CVE-2026-10643 · Severity: high · CVSS 8.7 · Published 2026-06-28

Zephyr, a real-time operating system used in embedded and IoT devices, contains a memory safety flaw in its networking component. An attacker can send a specially crafted network packet to a device, causing it to crash or potentially allowing the attacker to gain unauthorized control over the system. This could lead to service outages or the compromise of sensitive data handled by the device.

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

## Quick answers

**Is CVE-2026-10643 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-10643 being exploited in the wild.

**How severe is CVE-2026-10643?** High severity, with a CVSS score of 8.7, published 28 June 2026.

**Which products and versions are affected?** Zephyr Project Zephyr v3.6.0 through v4.4.0.

**Is there a fix for CVE-2026-10643?** A patch was published on 2026-06-28: Fix committed to Zephyr main branch. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-10643 attacked?** It is attacked over the network or with local access, in an operating system.

**Am I affected by CVE-2026-10643?** 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 heap-based buffer overflow exists in Zephyr's IP socket implementation within `subsys/net/lib/sockets/sockets_inet.c`. The `insert_pktinfo()` function validates user-supplied ancillary buffers (`msg_control`) using only the payload length while ignoring the size of the `cmsg` header. This discrepancy allows an out-of-bounds write of approximately 12 bytes. On systems with `CONFIG_USERSPACE` enabled, an unprivileged userspace thread can trigger this to corrupt kernel heap memory. The vulnerability is reachable via UDP/IP sockets when features like `IP_PKTINFO`, `IPV6_RECVPKTINFO`, or hardware timestamping are enabled and the application provides an undersized control buffer. The fix involves using `NET_CMSG_SPACE` to properly account for both header and data alignment.

## Affected products

- Zephyr Project Zephyr RTOS v3.6.0 through v4.4.0

## Timeline

- 2026-06-28: advisory: Vulnerability published and CVE-2026-10643 assigned.
- 2026-06-28: patched: Fix committed to Zephyr main branch.

## References

- [https://github.com/zephyrproject-rtos/zephyr](https://github.com/zephyrproject-rtos/zephyr)
- [https://github.com/zephyrproject-rtos/zephyr/commit/01fe77b2ec3885583f709a17c5203ce02bd77012](https://github.com/zephyrproject-rtos/zephyr/commit/01fe77b2ec3885583f709a17c5203ce02bd77012)

## Related threats

- [Zephyr UART wide-data syscall verifier NULL pointer dereference](https://junglewise.ai/threats/cve-2026-90834-the-user-mode-syscall-verifiers-for-the-16-bit-wide-data-uart-api)
- [Zephyr PTP port unvalidated logMessageInterval denial of service](https://junglewise.ai/threats/cve-2026-87042-the-ieee-1588-ptp-port-implementation-in-subsys-net-lib-ptp-port)
- [Zephyr HTTP server HTTP/2 buffer overflow via static file serving](https://junglewise.ai/threats/cve-2026-82391-the-http-2-front-end-of-the-zephyr-http-server-aliased-connection)
- [Zephyr OpenThread hardcoded default joiner credential](https://junglewise.ai/threats/cve-2026-19741-zephyr-s-openthread-integration-defined-config-openthread-joiner)
- [Zephyr ARM64 MMU ASID allocation collision in memory domain isolation](https://junglewise.ai/threats/cve-2026-19574-the-arm64-mmu-back-end-allocated-address-space-identifiers-asids)