# CVE-2026-41429: Improper validation of NBNS name_len in arduino-esp32 NetBIOS leads to memory corruption

> Remote attackers can trigger memory corruption in ESP32 devices via crafted NBNS packets when NetBIOS is enabled, potentially leading to code execution or crashes.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Apr 2026
- **Updated:** 27 Apr 2026
- **Also known as:** GHSA-92j9-c75g-2c5f

## What is CVE-2026-41429?

CVE-2026-41429 is a high-severity memory corruption vulnerability in espressif arduino-esp32, published on 24 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

arduino-esp32 is an Arduino core for the ESP32, ESP32-S2, ESP32-S3, ESP32-C3, ESP32-C6 and ESP32-H2 microcontrollers. Prior to 3.3.8, there is a remotely reachable memory corruption issue in the NBNS packet handling path. When NetBIOS is enabled by calling NBNS.begin(...), the device listens on UDP port 137 and processes untrusted NBNS requests from the local network.
The request parser trusts the attacker-controlled name_len field without enforcing a bound consistent with the fixed-size destination buffers used later in the flow. This vulnerability is fixed in 3.3.8.

Weakness: CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-41429?

It affects 1 product.


Products: Espressif Arduino-Esp32.

## How do I fix CVE-2026-41429?

No fix has been published for CVE-2026-41429 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-41429 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41429 exists.

## Other vulnerabilities in espressif arduino-esp32

- [CVE-2026-42854](https://insights.sbomify.com/CVE-2026-42854/): arduino-esp32: Stack buffer overflow in WebServer multipart boundary parsing leads to remote crash potential RCE (critical 9.8)
- [CVE-2026-42855](https://insights.sbomify.com/CVE-2026-42855/): arduino-esp32: Digest authentication URI mismatch bypass in WebServer allows cross-resource replay attack (high 7.5)
- [CVE-2019-12586](https://insights.sbomify.com/CVE-2019-12586/): Denial of service in n/a (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-41429 and fix it if it is affected.

What it is: CVE-2026-41429 is a high-severity memory corruption vulnerability in espressif arduino-esp32, published on 24 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41429 exists.

Affected product: espressif arduino-esp32. 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-2026-41429/ (Markdown: https://insights.sbomify.com/CVE-2026-41429/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-41429
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-41429
- OSV: https://osv.dev/vulnerability/CVE-2026-41429

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-41429/
Summaries are generated and may contain mistakes; the official description above is the record.