CVE-2024-42272 is a vulnerability identified in the Linux kernel, specifically within the network scheduler's connection tracking action (act_ct) component. The root cause stems from improper handling of padding bytes in the struct zones_ht_key, which is used as a key in a resizable hash table (rhashtable). A recent code change increased the size of the lookup key from 2 bytes to 16 bytes by adding a struct net pointer, but the padding bytes within this structure were not properly initialized. This leads to the use of uninitialized memory during rhashtable lookups, as detected by Kernel Memory Sanitizer (KMSAN) warnings. The uninitialized value usage occurs in multiple inline functions related to rhashtable lookups, such as rht_ptr_rcu, __rhashtable_lookup, rhashtable_lookup, and rhashtable_lookup_fast. The vulnerability manifests during the execution of tcf_ct_flow_table_get and related functions in net/sched/act_ct.c, which are involved in managing flow tables for connection tracking in the Linux traffic control subsystem. The issue could cause undefined behavior, including potential memory corruption or information leakage due to the use of uninitialized memory. However, no known exploits are reported in the wild at this time. The vulnerability affects multiple Linux kernel versions identified by specific commit hashes. The flaw is local in nature, requiring code execution within the kernel context, and is tied to network traffic control operations. The absence of a CVSS score indicates that the severity has not been formally assessed yet, but the technical details suggest a moderate risk due to the potential for memory corruption and instability in kernel networking components.

For European organizations, this vulnerability could impact any systems running affected Linux kernel versions, particularly those utilizing advanced network traffic control features such as connection tracking in high-performance or security-sensitive environments (e.g., data centers, ISPs, cloud providers, and enterprises with complex network policies). The flaw could lead to kernel instability, crashes, or potentially exploitable conditions that might allow privilege escalation or information disclosure if combined with other vulnerabilities. This is especially critical for organizations relying on Linux-based infrastructure for critical services, including telecommunications, financial services, and government networks. Disruptions or compromises in these environments could lead to service outages, data breaches, or compliance violations under regulations such as GDPR. Although no active exploits are known, the presence of uninitialized memory usage in kernel code is a common vector for subtle security issues, warranting prompt attention.

European organizations should prioritize updating their Linux kernel to versions where this vulnerability is patched once official fixes are released. Until patches are available, organizations should: 1) Limit the use of advanced traffic control features related to connection tracking (act_ct) if feasible, to reduce exposure. 2) Employ kernel hardening techniques such as Kernel Address Sanitizer (KASAN) or Kernel Memory Sanitizer (KMSAN) in testing environments to detect similar issues proactively. 3) Monitor kernel logs for unusual KMSAN warnings or kernel errors related to rhashtable lookups or traffic control modules. 4) Restrict local access to systems running vulnerable kernels to trusted users only, minimizing the risk of local exploitation. 5) Implement strict network segmentation and firewall rules to limit the ability of attackers to trigger vulnerable code paths remotely via crafted network traffic. 6) Engage with Linux distribution vendors for timely updates and advisories. 7) Conduct thorough regression testing after kernel upgrades to ensure stability of network functions.