CVE-2024-36940 is a vulnerability identified in the Linux kernel's pinctrl subsystem, specifically related to the pinctrl_enable() function. The root cause is a double free error involving the 'pctldev' structure. This structure is allocated using devm_pinctrl_register_and_init(), which manages its lifecycle via the device-managed (devm_) memory management framework. The 'pctldev' pointer is automatically freed by devm_pinctrl_dev_release(), which also frees associated pin descriptors and destroys a mutex. However, the vulnerable code erroneously attempts to free this pointer again within pinctrl_enable(), leading to a double free condition. Double free vulnerabilities can cause undefined behavior including memory corruption, program crashes, or potentially arbitrary code execution if exploited. Although no known exploits are currently reported in the wild, the vulnerability affects the core Linux kernel, which is widely deployed across servers, desktops, embedded systems, and IoT devices. The issue was published on May 30, 2024, and no CVSS score has been assigned yet. The vulnerability arises from incorrect resource management in kernel code, which could be triggered during device initialization or pin control operations. This flaw could be exploited by an attacker with the ability to invoke pinctrl_enable(), potentially leading to denial of service or escalation of privileges depending on the system context and kernel configuration. The vulnerability is relevant to all Linux kernel versions containing the faulty code, impacting a broad range of Linux-based systems until patched.

For European organizations, the impact of CVE-2024-36940 depends on their reliance on Linux-based infrastructure and devices. Linux is extensively used in enterprise servers, cloud environments, telecommunications equipment, industrial control systems, and embedded devices across Europe. A successful exploitation could cause system instability or crashes (denial of service), disrupting critical services. In worst-case scenarios, if combined with other vulnerabilities or specific kernel configurations, it might allow privilege escalation or arbitrary code execution, threatening confidentiality and integrity of sensitive data. Sectors such as finance, healthcare, manufacturing, and government agencies that depend on Linux servers or embedded Linux devices could face operational disruptions or data breaches. The vulnerability's exploitation requires triggering kernel-level pinctrl operations, which may limit remote exploitation but could be leveraged by local attackers or malicious insiders. Given the widespread use of Linux in European data centers and critical infrastructure, unpatched systems could be vulnerable to targeted attacks or malware leveraging this flaw to destabilize systems or gain elevated privileges.

European organizations should prioritize applying the official Linux kernel patches that address this double free vulnerability as soon as they become available. Until patches are deployed, organizations should: 1) Restrict access to systems running vulnerable Linux kernels, especially limiting untrusted local user access to prevent triggering pinctrl_enable(). 2) Employ kernel hardening techniques such as enabling Kernel Address Space Layout Randomization (KASLR), Kernel Page Table Isolation (KPTI), and other memory protection features to reduce exploitation risk. 3) Monitor system logs and kernel messages for unusual crashes or memory corruption symptoms that could indicate exploitation attempts. 4) Use security modules like SELinux or AppArmor to enforce strict access controls on device and kernel interfaces related to pinctrl operations. 5) For embedded or IoT devices, coordinate with vendors to ensure timely firmware updates incorporating the patched kernel. 6) Conduct thorough testing of updated kernels in staging environments before production deployment to avoid service disruptions. 7) Maintain an inventory of Linux kernel versions in use across the organization to identify and remediate vulnerable systems promptly.