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CVE-2026-39455: File Descriptor Exhaustion in F5 BIG-IP
Plataforma
linux
Componente
bigip
Corrigido em
21.0.0.2
CVE-2026-39455 affects F5 BIG-IP systems utilizing Lightweight Directory Access Protocol (LDAP) authentication. A misconfiguration can trigger an undisclosed traffic pattern, causing the httpd process to exhaust available file descriptors, resulting in a denial-of-service condition. This vulnerability impacts versions 16.1.0 through 21.0.0.2, and a fix is available in version 21.0.0.2.
Impacto e Cenários de Ataquetraduzindo…
Successful exploitation of CVE-2026-39455 can lead to a denial-of-service (DoS) attack, rendering the affected BIG-IP system unavailable. This disruption can impact critical services relying on the BIG-IP infrastructure, such as load balancing, web application delivery, and security features. The impact extends beyond the immediate system, potentially affecting applications and users dependent on the BIG-IP's functionality. While the vulnerability doesn't directly expose sensitive data, the DoS can disrupt operations and potentially mask other malicious activity. The blast radius is limited to the services managed by the affected BIG-IP instance.
Contexto de Exploraçãotraduzindo…
CVE-2026-39455 has been published on 2026-05-13. Its severity is rated HIGH (CVSS 7.5). Public proof-of-concept (POC) code is currently unavailable. The vulnerability is not listed on KEV or EPSS, suggesting a low to medium probability of exploitation in the short term. Monitor F5 security advisories and threat intelligence feeds for updates.
Inteligência de Ameaças
Status do Exploit
CISA SSVC
Vetor CVSS
O que significam essas métricas?
- Attack Vector
- Rede — explorável remotamente pela internet. Sem acesso físico ou local necessário.
- Attack Complexity
- Baixa — sem condições especiais. O atacante pode explorar de forma confiável.
- Privileges Required
- Nenhum — sem autenticação necessária para explorar.
- User Interaction
- Nenhuma — ataque automático e silencioso. A vítima não faz nada.
- Scope
- Inalterado — impacto limitado ao componente vulnerável.
- Confidentiality
- Nenhum — sem impacto na confidencialidade.
- Integrity
- Nenhum — sem impacto na integridade.
- Availability
- Alto — falha completa ou esgotamento de recursos. Negação de serviço total.
Software Afetado
Classificação de Fraqueza (CWE)
Linha do tempo
- Reservado
- Publicada
Mitigação e Soluções Alternativastraduzindo…
The primary mitigation for CVE-2026-39455 is upgrading to F5 BIG-IP version 21.0.0.2 or later, which includes the fix. If immediate upgrade is not feasible, implement temporary workarounds. Configure a Web Application Firewall (WAF) or proxy to limit or filter LDAP traffic to the BIG-IP system, specifically targeting the traffic pattern that triggers the file descriptor exhaustion. Review LDAP authentication configurations to ensure they adhere to security best practices and minimize unnecessary LDAP traffic. After upgrading, verify the fix by attempting to reproduce the vulnerability with the traffic pattern described in the advisory; the httpd process should not exhaust file descriptors.
Como corrigirtraduzindo…
Actualice a una versión corregida de BIG-IP. Las versiones afectadas incluyen 17.5.1.6, 17.1.3.2, 21.0.0.2 y versiones posteriores de 21.1.0. Consulte la documentación de F5 para obtener instrucciones detalladas de actualización y mitigación.
Perguntas frequentestraduzindo…
What is CVE-2026-39455 — File Descriptor Exhaustion in F5 BIG-IP?
CVE-2026-39455 is a HIGH severity vulnerability in F5 BIG-IP allowing LDAP authentication misconfigurations to exhaust file descriptors, causing a denial-of-service. It affects versions 16.1.0–21.0.0.2.
Am I affected by CVE-2026-39455 in F5 BIG-IP?
You are affected if you are running F5 BIG-IP versions 16.1.0 through 21.0.0.2 and have LDAP authentication enabled. Carefully review your LDAP configuration.
How do I fix CVE-2026-39455 in F5 BIG-IP?
Upgrade to F5 BIG-IP version 21.0.0.2 or later. As a temporary workaround, implement WAF rules to limit LDAP traffic.
Is CVE-2026-39455 being actively exploited?
Currently, there are no public reports of CVE-2026-39455 being actively exploited, but monitoring is crucial.
Where can I find the official F5 advisory for CVE-2026-39455?
Refer to the official F5 security advisory for CVE-2026-39455 on the F5 website: [https://www.f5.com/security/center/advisory/f5-security-advisory-26-07.html](https://www.f5.com/security/center/advisory/f5-security-advisory-26-07.html)
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