# CVE-2026-5590: net: ip/tcp: Null pointer dereference can be triggered by a race condition

> A race condition in Zephyr RTOS TCP teardown causes a null pointer dereference, leading to a system crash.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Apr 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-4vqm-pw24-g9jp

## What is CVE-2026-5590?

CVE-2026-5590 is a medium-severity vulnerability in Zephyrproject Zephyr, published on 5 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-5590?

It affects 1 product.


Products: Zephyrproject Zephyr.

## How do I fix CVE-2026-5590?

No fix has been published for CVE-2026-5590 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5590 being exploited?

There is no known exploitation of CVE-2026-5590 in the wild and no public exploit code.

## Other vulnerabilities in Zephyrproject Zephyr

- [CVE-2026-5067](https://insights.sbomify.com/CVE-2026-5067/): Out-of-bounds read/write in HTTP WebSocket upgrade via non-null-terminated Sec-WebSocket-Key (critical 9.8)
- [CVE-2022-3806](https://insights.sbomify.com/CVE-2022-3806/): Bluetooth HCI Error Handling Double Free (critical 9.8)
- [CVE-2017-14199](https://insights.sbomify.com/CVE-2017-14199/): Memory corruption in getaddrinfo (critical 9.8)
- [CVE-2018-1000800](https://insights.sbomify.com/CVE-2018-1000800/): Null dereference in n/a (critical 9.8)
- [CVE-2021-3329](https://insights.sbomify.com/CVE-2021-3329/): DOS: Incorrect handling of the initial HCI ACL_MTU handshake packet leads to crash of bluetooth host layer (critical 9.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5590 and fix it if it is affected.

What it is: CVE-2026-5590 is a medium-severity vulnerability in Zephyrproject Zephyr, published on 5 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-5590 in the wild and no public exploit code.

Affected product: Zephyrproject Zephyr. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-5590/ (Markdown: https://insights.sbomify.com/CVE-2026-5590/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5590
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5590
- OSV: https://osv.dev/vulnerability/CVE-2026-5590

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5590/
Summaries are generated and may contain mistakes; the official description above is the record.