# CVE-2021-27662: KT-1 Capture-replay

> Attackers can bypass authentication on Johnson Controls KT-1 door controllers by replaying recorded TCP packets.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Sep 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-fv2j-64xc-r4hr

## What is CVE-2021-27662?

CVE-2021-27662 is a high-severity vulnerability in Johnson Controls KT-1, published on 15 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The KT-1 door controller is susceptible to replay or man-in-the-middle attacks where an attacker can record and replay TCP packets. This issue affects Johnson Controls KT-1 all versions up to and including 3.01

Weakness: CWE-294 (Authentication Bypass by Capture-replay)

## Which versions are affected by CVE-2021-27662?

It affects 1 product.


Products: Johnsoncontrols Kantech Kt-1 Door Controller Firmware.

## How do I fix CVE-2021-27662?

No fix has been published for CVE-2021-27662 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-27662 being exploited?

There is no known exploitation of CVE-2021-27662 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27662 and fix it if it is affected.

What it is: CVE-2021-27662 is a high-severity vulnerability in Johnson Controls KT-1, published on 15 Sep 2021. 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-2021-27662 in the wild and no public exploit code.

Affected product: Johnson Controls KT-1. 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-2021-27662/ (Markdown: https://insights.sbomify.com/CVE-2021-27662/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27662
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27662
- OSV: https://osv.dev/vulnerability/CVE-2021-27662

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-27662/
Summaries are generated and may contain mistakes; the official description above is the record.