CVE-2026-11541: IBM CICS Transaction Gateway for Multiplatforms 9.1, 9.2, 9.3, and 10.1 IBM WebSphere Application Server 9.0,

This month

HIGH 7.4REMOTEUPGRADE

CVE-2026-11541 is a high-severity flaw (CVSS 7.4) affecting websphere application server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

IBM CICS Transaction Gateway for Multiplatforms 9.1, 9.2, 9.3, and 10.1 IBM WebSphere Application Server 9.0, and 8.5 and IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.6 are affected by an HTTP request smuggling vulnerability.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.4 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 64%)
CISA exploited list	No
Weakness	CWE-444
Published	2026-06-30
Last modified	2026-10-25

Publisher (CNA): IBM Corporation · Vendor: ibm

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

Am I affected?

Timeline

2026-06-30 22:16 UTCPublished CVE record published
2026-10-25 21:10 UTCUpdated Record last modified

ibm websphere application server UPGRADE

Affected: >= 8.5.0.0 and < 8.5.5.31 · >= 9.0.0.0 and < 9.0.5.29 · >= 17.0.0.3 and <= 26.0.0.6

Fixed in: 8.5.5.31, 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 8.5.5.31 (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-2026-11541?

websphere application server: upgrade to 8.5.5.31, 9.0.5.29. Exact commands for each OS are on this page.

Is CVE-2026-11541 being exploited?

CVE-2026-11541 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-2026-11541 affect?

CVE-2026-11541 affects websphere application server. Severity is high (CVSS 7.4). IBM CICS Transaction Gateway for Multiplatforms 9.1, 9.2, 9.3, and 10.1 IBM WebSphere Application Server 9.0, and 8.5 and IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.6 are affected by an HTTP request smuggling vulnera

How urgent is CVE-2026-11541?

Priority 40/100. High severity; Remotely exploitable, no login, no user action

Software pages

IBM WebSphere vulnerabilities

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References

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