# CVE-2026-6918: Denial of service in Eclipse OpenJ9

> A remote attacker can crash the JITServer by sending a crafted TCP message, causing a denial of service.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 May 2026
- **Updated:** 15 Jul 2026
- **Also known as:** GHSA-q393-vr4c-969r, UBUNTU-CVE-2026-6918

## What is CVE-2026-6918?

CVE-2026-6918 is a high-severity denial of service vulnerability in Eclipse OpenJ9, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In Eclipse Open9J versions 0.21 to 0.58, a pre-authentication remote attacker can crash JITServer by sending a 32-byte crafted TCP message.

Weakness: CWE-1286 (Improper Validation of Syntactic Correctness of Input), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-6918?

It affects 1 product.


Products: Eclipse Openj9.

## How do I fix CVE-2026-6918?

Upgrade to a fixed version.

## Is CVE-2026-6918 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6918 exists.

## Other vulnerabilities in Eclipse 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-2026-6918 and fix it if it is affected.

What it is: CVE-2026-6918 is a high-severity denial of service vulnerability in Eclipse OpenJ9, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-6918 exists.

Affected product: Eclipse 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-2026-6918/ (Markdown: https://insights.sbomify.com/CVE-2026-6918/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6918
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6918
- OSV: https://osv.dev/vulnerability/CVE-2026-6918

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6918/
Summaries are generated and may contain mistakes; the official description above is the record.