# CVE-2026-16439: Eclipse OpenJ9 : Using -Xtrace to trace method arguments can lead to buffer underflow

> Attackers can trigger a buffer underflow in Eclipse OpenJ9 by using the -Xtrace option to trace method arguments, potentially leading to code execution or crashes.

- **Severity:** Medium 5.8 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:A/VC:N/VI:H/VA:H/SC:N/SI:L/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 21 Jul 2026
- **Updated:** 22 Jul 2026
- **Also known as:** GHSA-pw53-4wcc-wm6v

## What is CVE-2026-16439?

CVE-2026-16439 is a medium-severity memory corruption vulnerability in Eclipse Foundation OpenJ9, published on 21 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

In Eclipse OpenJ9 versions up to 0.60, using -Xtrace to trace method arguments can lead to buffer underflow.

Weakness: CWE-124 (Buffer Underwrite)

## Which versions are affected by CVE-2026-16439?

It affects 1 product.


Products: Eclipse Openj9.

## How do I fix CVE-2026-16439?

Upgrade to a fixed version.

## Is CVE-2026-16439 being exploited?

There is no known exploitation of CVE-2026-16439 in the wild and no public exploit code.

## Other vulnerabilities in Eclipse Foundation OpenJ9

- [CVE-2021-41035](https://insights.sbomify.com/CVE-2021-41035/): Security feature bypass in Eclipse OMR (critical 9.8)
- [CVE-2020-27221](https://insights.sbomify.com/CVE-2020-27221/): Memory corruption in Eclipse OpenJ9 (critical 9.8)
- [CVE-2019-11772](https://insights.sbomify.com/CVE-2019-11772/): Memory corruption in Eclipse OpenJ9 (critical 9.8)
- [CVE-2018-12547](https://insights.sbomify.com/CVE-2018-12547/): Memory corruption in Eclipse OpenJ9 (critical 9.8)
- [CVE-2018-12549](https://insights.sbomify.com/CVE-2018-12549/): Null dereference in Eclipse OpenJ9 (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-16439 and fix it if it is affected.

What it is: CVE-2026-16439 is a medium-severity memory corruption vulnerability in Eclipse Foundation OpenJ9, published on 21 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-16439 in the wild and no public exploit code.

Affected product: Eclipse Foundation OpenJ9. 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-2026-16439/ (Markdown: https://insights.sbomify.com/CVE-2026-16439/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-16439
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-16439
- OSV: https://osv.dev/vulnerability/CVE-2026-16439

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-16439/
Summaries are generated and may contain mistakes; the official description above is the record.