# CVE-2021-27477: Memory corruption in JTEKT Corporation TOYOPUC PLC

> An attacker can cause a denial of service by sending invalid frames to JTEKT TOYOPUC PLCs, triggering a buffer overflow that stops the CPU.

- **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:** 1 Jul 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-xqpg-rjjg-58q9

## What is CVE-2021-27477?

CVE-2021-27477 is a high-severity memory corruption vulnerability in JTEKT Corporation TOYOPUC PLC, published on 1 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

When JTEKT Corporation TOYOPUC PLC versions PC10G-CPU, 2PORT-EFR, Plus CPU, Plus EX, Plus EX2, Plus EFR, Plus EFR2, Plus 2P-EFR, PC10P-DP, PC10P-DP-IO, Plus BUS-EX, Nano 10GX, Nano 2ET,PC10PE, PC10PE-16/16P, PC10E, FL/ET-T-V2H, PC10B,PC10B-P, Nano CPU, PC10P, and PC10GE receive an invalid frame, the outside area of a receive buffer for FL-net are overwritten. As a result, the PLC CPU detects a system error, and the affected products stop.

Weakness: CWE-787 (Out-of-bounds Write), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2021-27477?

It affects 22 products.


Products: Jtekt 2port-Efr Firmware, Jtekt Fl\/Et-T-V2h Firmware, Jtekt Nano 10gx Firmware, Jtekt Nano 2et Firmware, Jtekt Nano Cpu Firmware, Jtekt Pc10b-P Firmware, Jtekt Pc10b Firmware, Jtekt Pc10e Firmware, Jtekt Pc10g-Cpu Firmware, Jtekt Pc10ge Firmware, Jtekt Pc10p-Dp-Io Firmware, Jtekt Pc10p-Dp Firmware, Jtekt Pc10p Firmware, Jtekt Pc10pe-16\/16p Firmware, Jtekt Pc10pe Firmware, Jtekt Plus 2p-Efr Firmware, Jtekt Plus Bus-Ex Firmware, Jtekt Plus Cpu Firmware, Jtekt Plus Efr2 Firmware, Jtekt Plus Efr Firmware and 2 more.

## How do I fix CVE-2021-27477?

No fix has been published for CVE-2021-27477 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-27477 being exploited?

There is no known exploitation of CVE-2021-27477 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27477 and fix it if it is affected.

What it is: CVE-2021-27477 is a high-severity memory corruption vulnerability in JTEKT Corporation TOYOPUC PLC, published on 1 Jul 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-2021-27477 in the wild and no public exploit code.

Affected product: JTEKT Corporation TOYOPUC PLC. 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-2021-27477/ (Markdown: https://insights.sbomify.com/CVE-2021-27477/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27477
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27477
- OSV: https://osv.dev/vulnerability/CVE-2021-27477

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-27477/
Summaries are generated and may contain mistakes; the official description above is the record.