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CVE-2026-13773: IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 Approximately 50 generated CORBA stub classes in WebSphere

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This month
MEDIUM 6.0UPGRADE

CVE-2026-13773 is a medium-severity flaw (CVSS 6.0) 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 Approximately 50 generated CORBA stub classes in WebSphere eXtreme Scale's ogclient.jar call ORB.string_to_object() on an attacker-controlled IOR string during Java deserialization, turning any unfiltered ObjectInputStream sink in WAS into outbound IIOP SSRF to an attacker-chosen host; when chained with the IBM ORB's getUserException class-instantiation flaw (WAS-26), this SSRF escalates to remo

Why this priority

  • EPSS top 7%: very likely to be exploited

A fixed release or distro patch exists.

Risk facts

CVSS score6.0 (Medium)
Attack vectorNetwork (remote)
Attack complexityHigh
Privileges neededLow
User interactionNone
EPSS exploit chance6.1% (top 7%)
CISA exploited listNo
WeaknessCWE-918
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-2026-13773?

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

Is CVE-2026-13773 being exploited?

CVE-2026-13773 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-2026-13773 affect?

CVE-2026-13773 affects websphere extreme scale. Severity is medium (CVSS 6.0). IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 Approximately 50 generated CORBA stub classes in WebSphere eXtreme Scale's ogclient.jar call ORB.string_to_object() on an attacker-controlled IOR string during Java deserialization, turnin

How urgent is CVE-2026-13773?

Priority 44/100. EPSS top 7%: very likely to be exploited

Software pages

Java vulnerabilities · IBM WebSphere vulnerabilities

Related CVEs

References

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