# CVE-2026-45541: ESF-IDF: Remote Null Pointer Dereference in WebSocket Server

> A remote attacker can crash the WebSocket server by sending a malformed header, causing a denial of service before authentication.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Jun 2026
- **Updated:** 10 Jun 2026
- **Also known as:** GHSA-3j8v-xgrq-5vg8

## What is CVE-2026-45541?

CVE-2026-45541 is a high-severity vulnerability in espressif esp-idf, published on 10 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ESF-IDF is the Espressif Internet of Things (IOT) Development Framework. In versions 5.2.6, 5.3.5, 5.4.4, 5.5.4, and 6.0, a NULL-pointer dereference exists in the WebSocket subprotocol-negotiation path of the esp_http_server component. While parsing the client-supplied Sec-WebSocket-Protocol request header during the WebSocket handshake, the tokenisation result is dereferenced without a NULL check, so a malformed header value can crash the server before any application-level authentication runs. This issue has been patched in versions 5.2.7, 5.3.6, 5.4.5, 5.5.5, and 6.0.1.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-45541?

It affects 1 product.


Products: Espressif Esp-Idf.

## How do I fix CVE-2026-45541?

No fix has been published for CVE-2026-45541 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-45541 being exploited?

There is no known exploitation of CVE-2026-45541 in the wild and no public exploit code.

## Other vulnerabilities in espressif esp-idf

- [CVE-2026-45328](https://insights.sbomify.com/CVE-2026-45328/): ESF-IDF: Out-of-Bounds Write in ESP-TEE Secure Service Wrappers (critical 9.3)
- [CVE-2024-53406](https://insights.sbomify.com/CVE-2024-53406/): Auth bypass in n/a (high 8.8)
- [CVE-2021-28139](https://insights.sbomify.com/CVE-2021-28139/): Memory corruption in n/a (high 8.8)
- [CVE-2024-33453](https://insights.sbomify.com/CVE-2024-33453/): Information disclosure in n/a (high 8.1)
- [CVE-2019-12587](https://insights.sbomify.com/CVE-2019-12587/): Weak cryptography in n/a (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45541 and fix it if it is affected.

What it is: CVE-2026-45541 is a high-severity vulnerability in espressif esp-idf, published on 10 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-45541 in the wild and no public exploit code.

Affected product: espressif esp-idf. 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-2026-45541/ (Markdown: https://insights.sbomify.com/CVE-2026-45541/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45541
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45541
- OSV: https://osv.dev/vulnerability/CVE-2026-45541

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45541/
Summaries are generated and may contain mistakes; the official description above is the record.