# CVE-2021-28136: Memory corruption in n/a

> Attackers in radio range can crash ESP32 devices by replaying LMP packets during Bluetooth pairing due to improper handling in the ESP-IDF Bluetooth Classic implementation.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:A/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Sep 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-w488-94f6-hhmr

## What is CVE-2021-28136?

CVE-2021-28136 is a medium-severity memory corruption vulnerability in n/a, published on 7 Sep 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The Bluetooth Classic implementation in Espressif ESP-IDF 4.4 and earlier does not properly handle the reception of multiple LMP IO Capability Request packets during the pairing process, allowing attackers in radio range to trigger memory corruption (and consequently a crash) in ESP32 via a replayed (duplicated) LMP packet.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-28136?

It affects 1 product.


Products: Espressif Esp-Idf.

## How do I fix CVE-2021-28136?

No fix has been published for CVE-2021-28136 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-28136 being exploited?

There is no known exploitation of CVE-2021-28136 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [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-2021-28136 and fix it if it is affected.

What it is: CVE-2021-28136 is a medium-severity memory corruption vulnerability in n/a, published on 7 Sep 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-28136 in the wild and no public exploit code.

Affected product: n/a. 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-2021-28136/ (Markdown: https://insights.sbomify.com/CVE-2021-28136/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28136
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28136
- OSV: https://osv.dev/vulnerability/CVE-2021-28136

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28136/
Summaries are generated and may contain mistakes; the official description above is the record.