CVE-2026-7366: IBM DataPower Gateway Race Condition Flaw

CVE-2026-7366 Overview

CVE-2026-7366 is a race condition vulnerability in IBM DataPower Gateway that affects the handling of the built-in X-Client-IP header. Under concurrent request processing, request state is not properly isolated between requests. This allows X-Client-IP values to be contaminated across simultaneous transactions, enabling IP spoofing and disclosure of other clients' source IP addresses to unauthorized parties.

The flaw is classified under [CWE-362] (Concurrent Execution using Shared Resource with Improper Synchronization). It impacts multiple long-term support branches of the DataPower Gateway product line used as an API gateway and security enforcement point in enterprise environments.

Critical Impact
Concurrent requests can leak or spoof client IP addresses, breaking upstream logging, access controls, and rate-limiting decisions that depend on X-Client-IP.

Affected Products

IBM DataPower Gateway 11.0.0.0 through 11.0.0.1
IBM DataPower Gateway 10.6.0.0 through 10.6.0.9
IBM DataPower Gateway 10.5.0.0 through 10.5.0.21

Discovery Timeline

2026-08-12 - CVE-2026-7366 published to NVD
2026-08-12 - Last updated in NVD database

Technical Details for CVE-2026-7366

Vulnerability Analysis

The vulnerability resides in how IBM DataPower Gateway processes the built-in X-Client-IP header during concurrent request handling. DataPower assigns and reads the X-Client-IP value using shared state that is not correctly scoped to an individual request context. When two or more requests are processed in parallel, one request can observe or overwrite the X-Client-IP value belonging to another.

An attacker who can send requests to the gateway alongside legitimate traffic can influence which IP value downstream services receive. This affects backends that trust X-Client-IP for source attribution, audit logging, geolocation-based policy, or IP allowlisting. Because the header is often propagated to logs and Security Information and Event Management (SIEM) pipelines, contamination also corrupts forensic evidence.

Exploitation requires network access to the gateway and low privileges but a high attack complexity, since the attacker must reliably win the race window during concurrent processing.

Root Cause

The root cause is improper isolation of request state for the built-in X-Client-IP header. Shared storage used to compute or forward the header is accessed without adequate synchronization or per-request scoping, producing a classic time-of-check / time-of-use pattern under load.

Attack Vector

An attacker interacts with the gateway over the network by issuing crafted HTTP requests during periods of concurrent traffic. By timing requests to overlap with a target session, the attacker can either read another client's IP as reflected downstream or inject an arbitrary value that appears as the trusted X-Client-IP for a concurrent request. No user interaction is required.

No verified public exploit code is available. Refer to the IBM Support Page for vendor technical details.

Detection Methods for CVE-2026-7366

Indicators of Compromise

Log entries where the X-Client-IP value does not match the TCP source address recorded by the gateway or upstream load balancer.
Sudden changes in the geolocation or Autonomous System Number (ASN) associated with a single authenticated session.
Duplicate X-Client-IP values appearing across otherwise unrelated concurrent transactions.

Detection Strategies

Correlate gateway access logs with backend application logs to identify mismatches between the observed socket peer address and the propagated X-Client-IP header.
Baseline the normal distribution of X-Client-IP values per session identifier and alert on divergence during high-concurrency windows.
Enable DataPower transaction-level logging to capture the full request context, including the assigned X-Client-IP value at each processing stage.

Monitoring Recommendations

Ship DataPower and backend logs to a centralized analytics platform and run scheduled queries that compare header-derived IPs against network-layer source IPs.
Monitor authentication and rate-limiting subsystems that rely on X-Client-IP for anomalous decisions such as unexpected allowlist matches from foreign addresses.
Alert on bursts of concurrent requests targeting the same virtual service, which increase the likelihood of triggering the race window.

How to Mitigate CVE-2026-7366

Immediate Actions Required

Inventory all IBM DataPower Gateway instances and confirm running firmware against the affected version ranges.
Apply the fixed firmware release published by IBM as referenced in the IBM Support Page.
Treat the X-Client-IP header as untrusted for authentication or authorization decisions until patched.
Review recent access and audit logs for evidence of IP mismatches that may indicate exploitation.

Patch Information

IBM has issued a security bulletin covering DataPower Gateway versions 11.0.0.0 through 11.0.0.1, 10.6.0.0 through 10.6.0.9, and 10.5.0.0 through 10.5.0.21. Consult the IBM Support Page for the fixed firmware versions and upgrade guidance for each supported branch.

Workarounds

Strip or overwrite inbound X-Client-IP headers at an upstream proxy or load balancer before traffic reaches DataPower.
Use a custom, request-scoped header populated by trusted infrastructure to convey the true client IP to backend services.
Rely on the network-layer source address recorded by the perimeter load balancer for logging and policy decisions until the patch is deployed.

bash

# Example: strip client-supplied X-Client-IP at an upstream NGINX proxy
# so DataPower cannot be seeded with an attacker-controlled value.
proxy_set_header X-Client-IP "";
proxy_set_header X-Trusted-Client-IP $remote_addr;