# CVE-2021-21814: Memory corruption in AT&T

> An attacker can trigger memory corruption via a buffer overflow in HandleFileArg by providing a long command-line argument, potentially leading to code execution or crashes.

- **Severity:** High 7.8 (`CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Aug 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-9m22-mqrh-x6c3

## What is CVE-2021-21814?

CVE-2021-21814 is a high-severity memory corruption vulnerability in AT&T, published on 13 Aug 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Within the function HandleFileArg the argument filepattern is under control of the user who passes it in from the command line. filepattern is passed directly to strlen to determine the ending location of the char* passed in by the user, no checks are done to see if the passed in char* is longer than the staticly sized buffer data is memcpy‘d into, but after the memcpy a null byte is written to what is assumed to be the end of the buffer to terminate the char*, but without length checks, this null write occurs at an arbitrary offset from the buffer. An attacker can provide malicious input to trigger this vulnerability.

Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command)

## Which versions are affected by CVE-2021-21814?

It affects 1 product.


Products: Att Xmill.

## How do I fix CVE-2021-21814?

No fix has been published for CVE-2021-21814 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-21814 being exploited?

There is no known exploitation of CVE-2021-21814 in the wild and no public exploit code.

## Other vulnerabilities in AT&T

- [CVE-2022-26507](https://insights.sbomify.com/CVE-2022-26507/): Memory corruption in n/a (critical 9.8)
- [CVE-2021-21811](https://insights.sbomify.com/CVE-2021-21811/): Memory corruption in AT&T (high 8.1)
- [CVE-2021-21826](https://insights.sbomify.com/CVE-2021-21826/): Memory corruption in AT&T (high 8.1)
- [CVE-2021-21827](https://insights.sbomify.com/CVE-2021-21827/): Memory corruption in AT&T (high 8.1)
- [CVE-2021-21828](https://insights.sbomify.com/CVE-2021-21828/): Memory corruption in AT&T (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-21814 and fix it if it is affected.

What it is: CVE-2021-21814 is a high-severity memory corruption vulnerability in AT&T, published on 13 Aug 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-2021-21814 in the wild and no public exploit code.

Affected product: AT&T. 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-2021-21814/ (Markdown: https://insights.sbomify.com/CVE-2021-21814/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21814
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21814
- OSV: https://osv.dev/vulnerability/CVE-2021-21814

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-21814/
Summaries are generated and may contain mistakes; the official description above is the record.