CVE-2026-13476: IBM Informix Dynamic Server RCE Flaw

CVE-2026-13476 Overview

CVE-2026-13476 is a command injection vulnerability affecting IBM Informix Dynamic Server versions 14.10, 15.0, and 12.10. An unauthenticated remote attacker can execute arbitrary commands with service account privileges by supplying crafted input that the server fails to validate. The flaw maps to [CWE-78] (Improper Neutralization of Special Elements used in an OS Command). The vulnerability is reachable over the network without user interaction, expanding its exposure to any deployment that permits Informix service traffic.

Critical Impact
Unauthenticated attackers can execute arbitrary OS commands on affected Informix servers with service account privileges, enabling database compromise and lateral movement.

Affected Products

IBM Informix Dynamic Server 12.10
IBM Informix Dynamic Server 14.10
IBM Informix Dynamic Server 15.0

Discovery Timeline

2026-08-12 - CVE-2026-13476 published to NVD
2026-08-12 - Last updated in NVD database

Technical Details for CVE-2026-13476

Vulnerability Analysis

CVE-2026-13476 is an OS command injection issue in IBM Informix Dynamic Server. The server accepts user-supplied input and passes it into a command execution context without sufficient neutralization of shell metacharacters. An attacker who can reach the Informix service over the network can inject additional commands that execute in the security context of the Informix service account.

Because the vulnerability requires no authentication and no user interaction, exploitation can be scripted against exposed instances. Successful exploitation gives the attacker command execution on the underlying host with the privileges of the account running the Informix service, which is typically a privileged database service user. From that foothold, attackers can read or modify database contents, stage additional payloads, and pivot to internal systems.

Root Cause

The root cause is improper validation of user supplied input, classified under [CWE-78]. Input reaching a command execution path is not sanitized or safely parameterized, allowing shell metacharacters and command separators to alter the intended command.

Attack Vector

Exploitation requires network access to the Informix Dynamic Server listener. No credentials or prior authentication are needed. An attacker sends a malicious request containing command payloads within a vulnerable input field, and the server executes the injected commands. See the IBM Support Page for vendor-specific technical details.

// No verified public proof-of-concept is available.
// Refer to the IBM advisory for authoritative technical details.

Detection Methods for CVE-2026-13476

Indicators of Compromise

Unexpected child processes spawned by the Informix service account (for example, sh, bash, cmd.exe, powershell.exe).
Outbound network connections initiated by the Informix service process to unfamiliar hosts.
Shell metacharacters (;, |, &&, backticks) appearing in Informix connection or query logs.

Detection Strategies

Monitor process ancestry for the Informix service and alert on any non-database child processes.
Inspect network traffic to the Informix listener port for payloads containing shell metacharacters or command syntax.
Correlate authentication-less connections with subsequent process or file system activity on the database host.

Monitoring Recommendations

Enable verbose logging on Informix listeners and forward logs to a centralized analytics platform for review.
Baseline normal Informix service process behavior and alert on deviations such as new binaries, script interpreters, or outbound sockets.
Track file writes to system directories and cron or scheduled task changes originating from the Informix service account.

How to Mitigate CVE-2026-13476

Immediate Actions Required

Apply the IBM-supplied fix for Informix Dynamic Server 12.10, 14.10, and 15.0 as documented in the vendor advisory.
Restrict network access to the Informix listener using firewall rules so only authorized application hosts can connect.
Audit the Informix service account for excessive privileges and reduce them where operationally feasible.

Patch Information

IBM has published remediation guidance on the IBM Support Page. Administrators should consult the advisory for the fix pack or interim fix applicable to their installed version and platform.

Workarounds

Place Informix instances behind network segmentation that blocks untrusted sources from reaching the database port.
Enforce host-based firewall rules that allow inbound Informix traffic only from known application servers.
Run the Informix service under a least-privilege account to limit the impact of successful command execution.

bash

# Example: restrict Informix listener (default TCP 9088) to a trusted subnet using iptables
iptables -A INPUT -p tcp --dport 9088 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 9088 -j DROP