Deserialization in IBM Websphere Application Server

CVE-2026-9330

IBM WebSphere Application Server 9.0, and 8.5 is affected by an improper validation of user-supplied data during deserialization using the SAML Web Single Sign-On component. This could result in remote code execution via a crafted HTTP request when combined with a suitable gadget chain.

Vulnerability class: Insecure Deserialization

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.007 (50.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-9330: held from 0.005 to 0.007.

EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.002

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-9330?
CVE-2026-9330 is a high-severity vulnerability in IBM Websphere Application Server, classified under Deserialization of Untrusted Data. CVSS score: 8.5/10. Published 2026-06-01.
How severe is CVE-2026-9330?
High severity. CVSS v3 base score is 8.5 out of 10.