# CVE-2016-20042: TRN 3.6-23 Stack Buffer Overflow Local Code Execution

> Local attackers can execute arbitrary code via a stack buffer overflow in TRN by supplying oversized command-line arguments.

- **Severity:** High 8.6 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Mar 2026
- **Updated:** 30 Mar 2026
- **Also known as:** GHSA-g7ph-9gx9-ch48, UBUNTU-CVE-2016-20042

## What is CVE-2016-20042?

CVE-2016-20042 is a high-severity memory corruption vulnerability in trn Threaded USENET News Reader, published on 28 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

TRN 3.6-23 contains a stack buffer overflow vulnerability that allows local attackers to execute arbitrary code by supplying an oversized argument to the application. Attackers can craft a malicious command-line argument with 156 bytes of padding followed by a return address to overwrite the instruction pointer and execute shellcode with user privileges.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2016-20042?


## How do I fix CVE-2016-20042?

No fix has been published for CVE-2016-20042 yet. Limit exposure of the affected software until one is available.

## Is CVE-2016-20042 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2016-20042 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-20042 and fix it if it is affected.

What it is: CVE-2016-20042 is a high-severity memory corruption vulnerability in trn Threaded USENET News Reader, published on 28 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2016-20042 exists.

Affected product: trn Threaded USENET News Reader. 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-2016-20042/ (Markdown: https://insights.sbomify.com/CVE-2016-20042/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-20042
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-20042
- OSV: https://osv.dev/vulnerability/CVE-2016-20042

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From sbomify Insights: https://insights.sbomify.com/CVE-2016-20042/
Summaries are generated and may contain mistakes; the official description above is the record.