---
id: CVE-2026-5590
title: >-
  A race condition during TCP connection teardown can cause tcp_recv() to
  operate on a connection that has already been released
summary: >-
  A race condition during TCP connection teardown can cause tcp_recv() to
  operate on a connection that has already been released. If tcp_conn_search()
  returns NULL while processing a SYN packet, a NULL pointer derived from stale
  context da…
severity: medium
cvss: 6.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H'
cwe:
  - CWE-476
vendor: zephyrproject
product: zephyr
affected:
  - zephyr <= 4.3.0
published: '2026-04-05'
updated: '2026-07-08'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-5590'
references:
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-4vqm-pw24-g9jp
    label: vulnerabilities@zephyrproject.org
tags:
  - nvd
epss: 0.00198
epssPercentile: 0.09939
ingestedAt: '2026-07-08T13:51:10.455Z'
---

## Overview

A race condition during TCP connection teardown can cause tcp_recv() to operate on a connection that has already been released. If tcp_conn_search() returns NULL while processing a SYN packet, a NULL pointer derived from stale context data is passed to tcp_backlog_is_full() and dereferenced without validation, leading to a crash.

## Affected

- `zephyr <= 4.3.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.