# CVE-2020-24686: AC500 V2 webserver denial of service vulnerability

> Attackers can cause the ABB AC500 V2 PLC web visualization component to stop responding, denying remote visibility to legitimate users.

- **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:** 26 Feb 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-9f9p-5j8g-3cmm

## What is CVE-2020-24686?

CVE-2020-24686 is a high-severity denial of service vulnerability in ABB AC500 V2 products with onboard Ethernet, published on 26 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The vulnerabilities can be exploited to cause the web visualization component of the PLC to stop and not respond, leading to genuine users losing remote visibility of the PLC state. If a user attempts to login to the PLC while this vulnerability is exploited, the PLC will show an error state and refuse connections to Automation Builder. The execution of the PLC application is not affected by this vulnerability. This issue affects ABB AC500 V2 products with onboard Ethernet.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2020-24686?

It affects 6 products.


Products: Abb Pm554 Firmware, Abb Pm556 Firmware, Abb Pm564 Firmware, Abb Pm566 Firmware, Abb Pm572 Firmware, Abb Pm573 Firmware.

## How do I fix CVE-2020-24686?

No fix has been published for CVE-2020-24686 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-24686 being exploited?

There is no known exploitation of CVE-2020-24686 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-24686 and fix it if it is affected.

What it is: CVE-2020-24686 is a high-severity denial of service vulnerability in ABB AC500 V2 products with onboard Ethernet, published on 26 Feb 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-2020-24686 in the wild and no public exploit code.

Affected product: ABB AC500 V2 products with onboard Ethernet. 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-2020-24686/ (Markdown: https://insights.sbomify.com/CVE-2020-24686/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-24686
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-24686
- OSV: https://osv.dev/vulnerability/CVE-2020-24686

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-24686/
Summaries are generated and may contain mistakes; the official description above is the record.