# CVE-2021-40873: Use after free in n/a

> Remote attackers can cause a denial of service by sending crafted messages that trigger a double free, crashing the OPC UA server or client process.

- **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:** 10 Nov 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-4jmj-7wjp-8959

## What is CVE-2021-40873?

CVE-2021-40873 is a high-severity use after free vulnerability in n/a, published on 10 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in Softing Industrial Automation OPC UA C++ SDK before 5.66, and uaToolkit Embedded before 1.40. Remote attackers to cause a denial of service (DoS) by sending crafted messages to a client or server. The server process may crash unexpectedly because of a double free, and must be restarted.

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2021-40873?

It affects 7 products.


Products: Softing Datafeed Opc Suite, Softing Edgeconnector, Softing Opc, Softing Secure Integration Server, Softing Th Scope, Softing Uagates, Softing Uatoolkit Embedded.

## How do I fix CVE-2021-40873?

No fix has been published for CVE-2021-40873 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-40873 being exploited?

There is no known exploitation of CVE-2021-40873 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-42577](https://insights.sbomify.com/CVE-2021-42577/): Null dereference in n/a (high 7.5)
- [CVE-2021-40871](https://insights.sbomify.com/CVE-2021-40871/): Denial of service in n/a (high 7.5)
- [CVE-2021-42262](https://insights.sbomify.com/CVE-2021-42262/): Denial of service in n/a (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-40873 and fix it if it is affected.

What it is: CVE-2021-40873 is a high-severity use after free vulnerability in n/a, published on 10 Nov 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-2021-40873 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-2021-40873/ (Markdown: https://insights.sbomify.com/CVE-2021-40873/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40873
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40873
- OSV: https://osv.dev/vulnerability/CVE-2021-40873

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-40873/
Summaries are generated and may contain mistakes; the official description above is the record.