CVE-2024-57982 is a vulnerability identified in the Linux kernel's xfrm (IPsec) subsystem, specifically related to the state lookup mechanism. The issue arises due to a race condition between concurrent lookup and resize operations on the xfrm state hash table. The vulnerability is caused by the hash functions potentially observing an inconsistent or out-of-bounds hmask value when accessing the hash list array during state lookups. This happens because the update to the state_bydst pointer and the state_hmask value are not properly synchronized, allowing the lookup function to read a hash mask that is too large for the current hash list array. The root cause is that the existing synchronization mechanism, the xfrm_state_hash_generation seqlock, ensures retries but does not prevent the hash functions from temporarily accessing invalid memory regions. The fix involves prefetching the state_hmask and associated pointers to ensure consistency, and adding lockdep assertions to clarify that certain helper functions are unsafe for Read-Copy-Update (RCU) side operations. Additionally, the xfrm_state_lookup_byaddr() function currently uses a spinlock instead of RCU, which is considered an oversight and is planned to be corrected in future patches. This vulnerability could lead to out-of-bounds memory reads during state lookups, potentially causing kernel crashes or information disclosure. However, no known exploits are reported in the wild as of the publication date.

For European organizations, this vulnerability poses a risk primarily to systems running Linux kernels that include the vulnerable xfrm IPsec implementation. Since IPsec is widely used for secure communications, including VPNs and encrypted tunnels, exploitation could disrupt secure network communications or lead to kernel crashes, resulting in denial of service. In environments where sensitive data is transmitted over IPsec tunnels, an out-of-bounds read could potentially be leveraged for information disclosure, although exploitation complexity is moderate due to the need for concurrent operations and kernel-level access. Critical infrastructure, financial institutions, and enterprises relying on Linux-based VPN gateways or routers could experience service interruptions or data exposure. The lack of known exploits reduces immediate risk, but the vulnerability should be addressed promptly to prevent future attacks, especially given the strategic importance of secure communications in European digital infrastructure.

European organizations should prioritize updating their Linux kernel to the latest patched version that addresses CVE-2024-57982. Specifically, kernel maintainers have implemented prefetching of state_hmask and associated pointers to ensure consistency during concurrent lookups and resizes. Organizations should audit their use of IPsec and xfrm subsystems to identify affected systems, particularly VPN gateways, routers, and firewalls running Linux. Where immediate patching is not feasible, applying kernel-level mitigations such as disabling or limiting concurrent state resize operations or restricting access to IPsec configuration interfaces can reduce exposure. Additionally, monitoring kernel logs for unusual crashes or memory access errors related to xfrm state lookups can help detect exploitation attempts. Network segmentation and strict access controls to Linux systems handling IPsec traffic further reduce risk. Finally, organizations should track Linux kernel updates and security advisories to apply future fixes, including the planned replacement of spinlocks with RCU in xfrm_state_lookup_byaddr().