CVE-2026-93907 Overview
CVE-2026-93907 is an authentication bypass vulnerability affecting IBM WebSphere Application Server versions 8.5 and 9.0. The flaw resides in the Common Secure Interoperability Version 2 (CSIv2) inbound propagation handler. A remote attacker can exploit this weakness over the network without prior authentication or user interaction. Successful exploitation allows an unauthenticated attacker to bypass authentication controls and gain access to protected application resources. The vulnerability is tracked under [CWE-287] (Improper Authentication) and carries high impact to confidentiality, integrity, and availability.
Critical Impact
Unauthenticated remote attackers can bypass CSIv2 authentication on IBM WebSphere Application Server 8.5 and 9.0, exposing hosted enterprise applications to unauthorized access.
Affected Products
- IBM WebSphere Application Server 8.5
- IBM WebSphere Application Server 9.0
- Deployments relying on CSIv2 inbound authentication propagation
Discovery Timeline
- 2026-10-13 - CVE-2026-93907 published to the National Vulnerability Database
- 2026-10-14 - Last updated in NVD database
Technical Details for CVE-2026-93907
Vulnerability Analysis
The vulnerability resides in the CSIv2 inbound propagation handler of IBM WebSphere Application Server. CSIv2 is the CORBA-based protocol used by WebSphere to transport identity and authentication tokens between application server tiers. The inbound handler processes authentication assertions arriving from upstream callers. A flaw in how the handler validates these propagated identity tokens allows a remote caller to pass authentication checks without supplying valid credentials. An attacker reaching the CSIv2 listener port can craft a request that the handler accepts as an authenticated principal. This grants access to secured Enterprise JavaBeans (EJB) and other resources that depend on CSIv2 identity assertions for access control.
Root Cause
The root cause is improper authentication logic within the CSIv2 inbound propagation code path, categorized as [CWE-287]. The handler trusts attributes of the inbound security context without fully verifying the authenticity of the asserting identity. This design gap allows forged or malformed assertions to satisfy the authentication check.
Attack Vector
The attack vector is remote and unauthenticated. An attacker needs network reach to the WebSphere CSIv2 listener, typically exposed on the Object Request Broker (ORB) port. No user interaction is required. The high attack complexity reflects conditions the attacker must satisfy to produce a request the handler accepts, such as valid protocol framing and timing. Refer to the IBM Support Page for product-specific technical details.
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Stop Identity AttacksDetection Methods for CVE-2026-93907
Indicators of Compromise
- Unexpected successful authentications on EJB or Jakarta Enterprise Beans endpoints originating from external or unmanaged subnets.
- CSIv2 inbound requests on the ORB listener port from IP addresses outside normal application-tier communication patterns.
- WebSphere SystemOut.log entries showing identity assertions for principals that did not perform an interactive login.
Detection Strategies
- Enable CSIv2 trace logging on the application server and review inbound security context creation events for anomalies.
- Correlate ORB listener connections with upstream server inventories to identify unauthorized clients initiating CSIv2 sessions.
- Baseline authenticated principal activity per application and alert on new principals accessing secured EJB methods.
Monitoring Recommendations
- Forward WebSphere security audit logs and SystemOut.log to a centralized logging platform for correlation.
- Monitor network flows to WebSphere ORB and CSIv2 ports and alert on connections from non-approved sources.
- Track administrative console and JMX activity for post-exploitation actions following suspicious authentications.
How to Mitigate CVE-2026-93907
Immediate Actions Required
- Apply the IBM security update for WebSphere Application Server 8.5 and 9.0 as documented on the IBM Support Page.
- Restrict network access to the CSIv2 and ORB listener ports so only trusted application tiers can reach them.
- Audit recent authentication and administrative activity on affected servers for signs of unauthorized access.
Patch Information
IBM has published remediation guidance and fix availability for WebSphere Application Server 8.5 and 9.0. Review the IBM Support Page for interim fixes, APAR references, and version-specific installation instructions. Apply the vendor-supplied fix on all affected nodes, including Deployment Manager, node agents, and application servers, then restart services to activate the updated CSIv2 handler.
Workarounds
- Disable CSIv2 identity assertion inbound propagation where not required by application topology.
- Enforce transport-level mutual TLS between WebSphere nodes to limit which clients can establish CSIv2 sessions.
- Place affected servers behind network segmentation that blocks CSIv2 traffic from untrusted zones until patching completes.
# Configuration example
# Review CSIv2 inbound settings via wsadmin after patching
wsadmin.sh -lang jython -c "AdminTask.listCSIInboundInfo()"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
