CVE-2026-6918: In Eclipse Open9J versions 0.21 to 0.58, a pre-authentication remote attacker can crash JITServer by sending a

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HIGH 7.5REMOTEUPGRADE

CVE-2026-6918 is a high-severity flaw (CVSS 7.5) affecting openj9. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Weakness	CWE-125, CWE-1286
Published	2026-05-05
Last modified	2026-10-26

Publisher (CNA): Eclipse Foundation · Vendor: eclipse

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-05 13:16 UTCPublished CVE record published
2026-10-26 19:10 UTCUpdated Record last modified

eclipse openj9 UPGRADE

Affected: >= 0.21.0 and < 0.59.0

Fixed in: 0.59.0

Safe to downgrade to: a release before 0.21.0

1. Check installed version

apt-cache policy openj9 || rpm -q openj9 || openj9 --version

2. UPGRADE to 0.59.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade openj9

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openj9

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.21.0 (Debian / Ubuntu)

apt-cache madison openj9 sudo apt install openj9=<VERSION_BEFORE_0.21.0> sudo apt-mark hold openj9

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list openj9 sudo dnf downgrade openj9-<VERSION_BEFORE_0.21.0> sudo dnf versionlock add openj9

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-6918?

openj9: upgrade to 0.59.0. Exact commands for each OS are on this page.

Is CVE-2026-6918 being exploited?

CVE-2026-6918 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-6918 affect?

CVE-2026-6918 affects openj9. Severity is high (CVSS 7.5). 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.

How urgent is CVE-2026-6918?

Priority 47/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-16439 CRITICAL 9.1 UPGRADE In Eclipse OpenJ9 versions up to 0.60, using -Xtrace to trace method arguments can lead to buffer underflow.
CVE-2026-16441 CRITICAL 9.6 UPGRADE In Eclipse OpenJ9 versions up to 0.60, when executing class files where a previously concrete superclass metho

References

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