SERIOUS VULNERABILITY DISCOVERED IN LINUX KERNEL AND ZERO-DAY IN CPANEL: TWO CRITICAL ISSUES THAT PUT IT INFRASTRUCTURES AT RISK In recent days, the cybersecurity community has had to deal with two particularly concerning vulnerabilities: a serious flaw in the Linux kernel, active for years, and a zero-day in cPanel actively exploited for months. Both threats could have significant consequences for IT infrastructures worldwide.

The "Copy Fail" vulnerability in the Linux kernel: an underestimated danger

Researchers at Theori have discovered a high-severity vulnerability (CVE-2026-31431), nicknamed "Copy Fail," that allows local privilege escalation (LPE) in the Linux kernel. This defect, present in almost all major Linux distributions for the past seven years, is particularly concerning because:
  • Wide distribution: Affects Linux distributions released since 2017, impacting servers, IoT devices, and embedded systems
  • Reliable escalation: Allows local attackers to gain system administrator privileges
  • Proof-of-concept available: A working exploit has already been published online, facilitating exploitation
    • The severity of the vulnerability is heightened by the fact that it does not require user interaction and can be exploited by unprivileged users to gain complete system access. Organizations running Linux systems are strongly advised to apply security patches as soon as they become available.

    The zero-day in cPanel: actively exploited for months

    Another significant threat emerges from the discovery of an authentication bypass vulnerability (CVE-2026-41940) in cPanel, a popular control panel for managing web hosting accounts. This vulnerability:
  • Has been actively exploited since early February 2026, long before the patch release
  • Allows attackers to bypass authentication and access administrative features
  • Enables the execution of arbitrary commands on hosting servers
    • The situation is particularly severe because attackers did not have to wait for the technical disclosure of the vulnerability by watchTowr researchers to start exploiting it. This suggests they may have been aware of the flaw long before its public announcement.

    Combined risks and recommendations

    The simultaneous existence of these two critical vulnerabilities poses a significant threat to many organizations. Specifically:
  • Unpatched Linux servers could be compromised through the kernel vulnerability
  • Vulnerable cPanel control panels can be exploited to gain full access to hosting servers
  • The combination of these vulnerabilities could allow attackers to move laterally within corporate networks
    • The main recommendations to mitigate these risks include: 1. Immediately update all Linux distributions to patched versions 2. Apply the security patch for cPanel as soon as it becomes available 3. Closely monitor systems for signs of suspicious activity 4. Implement additional security measures, such as the principle of least privilege and advanced activity monitoring

    Community response

    The cybersecurity community is responding quickly to these threats. CISA and Microsoft have already issued public advisories, and many security solution providers are developing detection and mitigation tools specific to these vulnerabilities. The discovery of these two critical vulnerabilities underscores the importance of keeping all software components up to date and implementing robust security practices. While developers work to fix these defects, organizations must act quickly to protect their infrastructures from potential attacks.

    Further reading

    To delve deeper into these threats and the cybersecurity community's responses, it is recommended to consult the comprehensive reports published by Theori, watchTowr, and CISA.

    Economic and sectoral impact

    Vulnerabilities in the Linux kernel and cPanel could have significant economic consequences. According to Gartner data, privacy violation fines in the United States reached $3.425 billion in 2025, with an upward trend expected until 2028. This situation could worsen with the increase in attacks based on vulnerabilities like those just discovered. The most affected sectors could be:
  • Hosting and cloud computing: The cPanel vulnerability is particularly concerning for hosting service providers, which could suffer severe compromises
  • E-commerce: E-commerce sites using Linux servers could be targeted by attacks that compromise customer data
  • Financial services: Trading platforms like Robinhood have already been hit by phishing campaigns, and these new vulnerabilities could worsen the situation

    • Advanced technical responses

    In addition to the basic measures recommended earlier, some advanced solutions are emerging: 1. IPFire DNS Firewall: The IPFire Core Update 201 introduces domain blocking at the DNS level, which could be useful for preventing attacks based on these vulnerabilities 2. AI model provenance tools: Cisco has released an open-source toolkit to verify the provenance of AI models, which could be useful for ensuring the integrity of security systems 3. Advanced monitoring: SOC solutions are evolving to adopt more effective metrics, such as those suggested by the UK National Cyber Security Centre

    New related threats

    While organizations focus on mitigating these vulnerabilities, other threats are emerging:
  • Emerging threat groups: UNC6692, a new threat group documented by Google, is exploiting Microsoft Teams to penetrate corporate networks
  • Windows Shell vulnerabilities: CVE-2026-32202, a zero-click vulnerability, is being actively exploited, according to CISA and Microsoft advisories
  • Defective ransomware: The Vect ransomware has a bug that makes it essentially a data wiper, representing a new threat to organizations

    • Legal and compliance implications

    The discovery of these vulnerabilities raises important legal issues:
  • Shared responsibility: Microsoft Exchange Online's shared responsibility model underscores the need for organizations to protect their own data, identities, and configurations
  • Data breaches: Organizations that do not promptly update their systems may face serious legal consequences in case of data breaches
  • Regulatory compliance: Privacy regulations such as GDPR and CCPA require organizations to adopt adequate measures to protect personal data

    • Long-term strategies

    To protect infrastructures from these and future threats, organizations should consider: 1. Implementing a security framework: Adopting a comprehensive security framework such as NIST CSF or ISO 27001 2. Continuous training: Investing in continuous training of personnel on cybersecurity 3. Security automation: Implementing automation solutions for incident detection and response 4. Collaboration with the community: Participating in security information-sharing initiatives such as ISACs The discovery of these critical vulnerabilities serves as a reminder of the complexity and continuous evolution of the cybersecurity landscape. While organizations work to mitigate these immediate risks, it is essential to adopt a strategic and long-term approach to cybersecurity. Collaboration between solution providers, security researchers, and user organizations will be key to effectively addressing these challenges.

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