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CVE-2026-9311: IBM WebSphere Application Server 9.0, and 8.5 is vulnerable to remote code execution caused by the bypass of s

47
This month
CRITICAL 9.0REMOTEUPGRADE

CVE-2026-9311 is a critical-severity flaw (CVSS 9.0) affecting websphere application server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

IBM WebSphere Application Server 9.0, and 8.5 is vulnerable to remote code execution caused by the bypass of security controls.

Why this priority

  • Critical severity
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score9.0 (Critical)
Attack vectorNetwork (remote)
Attack complexityHigh
Privileges neededNone
User interactionNone
EPSS exploit chance0.5% (top 57%)
CISA exploited listNo
WeaknessCWE-94
Published2026-06-01
Last modified2026-07-22
Publisher (CNA): IBM Corporation · Vendor: ibm

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Last updated 2026-07-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

ibm websphere application server UPGRADE
Affected: >= 8.5.0.0 and < 8.5.5.30 · >= 9.0.0.0 and < 9.0.5.29
Fixed in: 8.5.5.30, 9.0.5.29
Safe to downgrade to: a release before 8.5.0.0
1. Check installed version
apt-cache policy websphere-application-server || rpm -q websphere-application-server || websphere-application-server --version
2. UPGRADE to 8.5.5.30 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade websphere-application-server
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade websphere-application-server
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 8.5.0.0 (Debian / Ubuntu)
apt-cache madison websphere-application-server sudo apt install websphere-application-server=<VERSION_BEFORE_8.5.0.0> sudo apt-mark hold websphere-application-server
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list websphere-application-server sudo dnf downgrade websphere-application-server-<VERSION_BEFORE_8.5.0.0> sudo dnf versionlock add websphere-application-server
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-2026-9311?

websphere application server: upgrade to 8.5.5.30, 9.0.5.29. Exact commands for each OS are on this page.

Is CVE-2026-9311 being exploited?

CVE-2026-9311 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-2026-9311 affect?

CVE-2026-9311 affects websphere application server. Severity is critical (CVSS 9.0). IBM WebSphere Application Server 9.0, and 8.5 is vulnerable to remote code execution caused by the bypass of security controls.

How urgent is CVE-2026-9311?

Priority 47/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

IBM WebSphere vulnerabilities

Related CVEs

References

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