F5 BIG-IP LDAP Auth Causes httpd FD Exhaustion
CVE-2026-39455 Published on May 13, 2026
BIG-IP Configuration utility vulnerability
When the BIG-IP Configuration utility is configured to use Lightweight Directory Access Protocol (LDAP) authentication, undisclosed traffic can cause the httpd process to exhaust the available file descriptors. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Vulnerability Analysis
CVE-2026-39455 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
Missing Release of Resource after Effective Lifetime
The software does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed. When a resource is not released after use, it can allow attackers to cause a denial of service by causing the allocation of resources without triggering their release. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.
Products Associated with CVE-2026-39455
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Affected Versions
F5 BIG-IP:- Version 21.1.0 and below * is unaffected.
- Version 21.0.0 and below 21.0.0.2 is affected.
- Version 17.5.0 and below 17.5.1.6 is affected.
- Version 17.1.0 and below 17.1.3.2 is affected.
- Version 16.1.0 and below * is affected.