What is CVE-2026-9311?

CVE-2026-9311 is a critical-severity vulnerability in IBM Websphere Application Server, classified under Code Injection. CVSS score: 9.0/10. Published 2026-06-01.

How severe is CVE-2026-9311?

Critical severity. CVSS v3 base score is 9.0 out of 10.

RCE in IBM Websphere Application Server

CVE-2026-9311

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

Vulnerability class: RCE (Remote Code Execution)

Published 2026-06-01 · last modified 2026-07-22.

CVSS v3 metric

CVSS v3 base score 9.0 (Critical). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.006 (49.6th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 49.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001

Affected products

IBM Websphere Application Server — versions 9.0, 8.5
IBM Websphere Application Server

Weakness classification (CWE)

CWE-94 — Code Injection

References

www.ibm.com/support/pages/node/7274733 (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-9311?: CVE-2026-9311 is a critical-severity vulnerability in IBM Websphere Application Server, classified under Code Injection. CVSS score: 9.0/10. Published 2026-06-01.
How severe is CVE-2026-9311?: Critical severity. CVSS v3 base score is 9.0 out of 10.