PatchSiren cyber security CVE debrief

CVE-2026-5516 IBM CVE debrief

IBM WebSphere Application Server Liberty 22.0.0.11 through 26.0.0.5 contains a medium-severity timing window vulnerability that could allow remote attackers to bypass security controls under limited conditions. The vulnerability requires high attack complexity and high privileges to exploit, with network access but no user interaction needed. Successful exploitation results in high confidentiality impact (information disclosure) with no integrity or availability impact. The CVE was published on 2026-05-27 and is currently undergoing analysis in the NVD. IBM has published a security bulletin with remediation guidance.

Vendor: IBM
Product: WebSphere Application Server - Liberty
CVSS: MEDIUM 4.4
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-05-27
Original CVE updated: 2026-05-27
Advisory published: 2026-05-27
Advisory updated: 2026-05-27

Who should care

Organizations running IBM WebSphere Application Server Liberty versions 22.0.0.11 through 26.0.0.5, particularly those with externally exposed administrative interfaces or multi-tenant deployments where privilege boundaries are critical.

Technical summary

A timing window vulnerability in IBM WebSphere Application Server Liberty 22.0.0.11 through 26.0.0.5 allows remote attackers with high privileges to bypass security controls under limited conditions. The attack requires high complexity and network access, resulting in potential information disclosure (C:H) without affecting integrity or availability. The root cause appears to be a race condition or synchronization issue in security enforcement that can be exploited during a specific timing window.

Defensive priority

medium

Recommended defensive actions

Review IBM security bulletin for available fixes and upgrade to a patched version of WebSphere Application Server Liberty
Assess exposure of Liberty deployments within the affected version range (22.0.0.11 through 26.0.0.5)
Monitor IBM support pages for updated security patches as the vulnerability is undergoing analysis
Implement network segmentation and access controls to limit exposure of administrative interfaces
Review application logs for anomalous access patterns that may indicate attempted exploitation of timing windows

Evidence notes

CVSS 3.1 vector: AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N. Affected versions: 22.0.0.11 through 26.0.0.5. Vendor confirmed via IBM PSIRT.

Official resources

2026-05-27