# CVE-2020-26557: Auth bypass in n/a

> A nearby attacker can brute-force the Bluetooth Mesh provisioning AuthValue to bypass authentication and join the network.

- **Severity:** High 7.5 (`CVSS:3.1/AV:A/AC:H/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:** Yes
- **Published:** 24 May 2021
- **Updated:** 4 Nov 2025
- **Also known as:** GHSA-gprg-wq36-vj82, ROOT-OS-UBUNTU-2204-CVE-2020-26557, UBUNTU-CVE-2020-26557

## What is CVE-2020-26557?

CVE-2020-26557 is a high-severity authentication bypass vulnerability in n/a, published on 24 May 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Mesh Provisioning in the Bluetooth Mesh profile 1.0 and 1.0.1 may permit a nearby device (without possession of the AuthValue used in the provisioning protocol) to determine the AuthValue via a brute-force attack (unless the AuthValue is sufficiently random and changed each time).

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2020-26557?

It affects 1 product.


Products: Bluetooth Mesh Profile.

## How do I fix CVE-2020-26557?

Apply the vendor's patch.

## Is CVE-2020-26557 being exploited?

There is no known exploitation of CVE-2020-26557 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-26559](https://insights.sbomify.com/CVE-2020-26559/): Auth bypass in n/a (high 8.8)
- [CVE-2020-26560](https://insights.sbomify.com/CVE-2020-26560/): Auth bypass in n/a (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-26557 and fix it if it is affected.

What it is: CVE-2020-26557 is a high-severity authentication bypass vulnerability in n/a, published on 24 May 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-2020-26557 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-2020-26557/ (Markdown: https://insights.sbomify.com/CVE-2020-26557/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-26557
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-26557
- OSV: https://osv.dev/vulnerability/CVE-2020-26557

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-26557/
Summaries are generated and may contain mistakes; the official description above is the record.