F5 on Wednesday announced fixes for over 19 high-severity and 32 medium-severity vulnerabilities impacting BIG-IP, BIG-IQ, and NGINX.
Based on the CVSS score, the most severe of the resolved issues is CVE-2026-42945 (CVSS v4.0 score of 9.2), a denial-of-service (DoS) condition in NGINX’s ngx_http_rewrite_module module.
The bug allows an unauthenticated attacker to send crafted HTTP requests that, combined with certain conditions beyond the attacker’s control, could trigger a heap buffer overflow and a restart. If Address Space Layout Randomization (ASLR) is disabled, the flaw can be exploited for code execution.
Next in line is CVE-2026-41225 (CVSS v4.0 score of 8.6), a weakness in iControl REST that could allow an authenticated attacker who has at least Manager permissions to create configuration objects, leading to command execution.
“This vulnerability may allow a highly privileged attacker with network access to the affected iControl REST endpoint through the BIG-IP management port or self IP addresses to escalate their privileges or bypass Appliance mode restrictions. In appliance mode deployments, a successful exploit can allow the attacker to cross a security boundary. There is no data plane exposure; this is a control plane issue only,” F5 explains.
On Wednesday, the company also announced fixes for high-severity remote code execution (RCE) and remote command injection vulnerabilities (CVE-2026-41957, CVE-2026-34176, CVE-2026-39459) in BIG-IP that require authentication.
Of the remaining high-severity flaws, one can lead to restriction bypass, another to arbitrary file tampering, and 12 to denial-of-service (DoS) conditions, mainly by causing the Traffic Management Microkernel (TMM) to terminate.
The medium-severity issues that F5 addressed this week could lead to security protection bypass, privilege escalation, information disclosure, arbitrary system command execution, DoS conditions, code injection, and arbitrary local file tampering.
None of these vulnerabilities appears to have been exploited in the wild. Additional information can be found in F5’s quarterly security notification.
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