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CVE-2026-9002: IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 could allow an adjacent attacker to cause a denial of serv

27
Routine
MEDIUM 6.5UPGRADE

CVE-2026-9002 is a medium-severity flaw (CVSS 6.5) affecting websphere extreme scale. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 could allow an adjacent attacker to cause a denial of service due to improper validation in the XDF decoder. The application processes deeply nested Protocol Buffers messages and attacker-controlled length prefixes without sufficient bounds checking, which may allow an attacker on the same network to trigger a StackOverflowError or OutOfMemoryError, resulting in a crash of the WebSphere Applicat

Why this priority

  • No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score6.5 (Medium)
Attack vectorAdjacent network
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance0.3% (top 81%)
CISA exploited listNo
WeaknessCWE-400
Published2026-06-30
Last modified2026-10-25
Publisher (CNA): IBM Corporation · Vendor: ibm

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Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

ibm websphere extreme scale UPGRADE
Affected: >= 8.6.1.0 and <= 8.6.1.6
Fixed in: newer than 8.6.1.6
Safe to downgrade to: a release before 8.6.1.0
1. Check installed version
apt-cache policy websphere-extreme-scale || rpm -q websphere-extreme-scale || websphere-extreme-scale --version
2. UPGRADE to newer than 8.6.1.6 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade websphere-extreme-scale
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade websphere-extreme-scale
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 8.6.1.0 (Debian / Ubuntu)
apt-cache madison websphere-extreme-scale sudo apt install websphere-extreme-scale=<VERSION_BEFORE_8.6.1.0> sudo apt-mark hold websphere-extreme-scale
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list websphere-extreme-scale sudo dnf downgrade websphere-extreme-scale-<VERSION_BEFORE_8.6.1.0> sudo dnf versionlock add websphere-extreme-scale
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-2026-9002?

websphere extreme scale: upgrade to newer than 8.6.1.6. Exact commands for each OS are on this page.

Is CVE-2026-9002 being exploited?

CVE-2026-9002 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-2026-9002 affect?

CVE-2026-9002 affects websphere extreme scale. Severity is medium (CVSS 6.5). IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 could allow an adjacent attacker to cause a denial of service due to improper validation in the XDF decoder. The application processes deeply nested Protocol Buffers messages and attacker-

How urgent is CVE-2026-9002?

Priority 27/100. No elevated risk signals yet.

Software pages

IBM WebSphere vulnerabilities

Related CVEs

References

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