CVE-2022-49586 is a concurrency vulnerability in the Linux kernel related to the handling of the sysctl_tcp_fastopen parameter. The vulnerability arises because the sysctl_tcp_fastopen value can be read concurrently while it is being modified, leading to potential data races. Specifically, the Linux kernel's TCP stack reads the sysctl_tcp_fastopen variable without proper synchronization, which can cause inconsistent or corrupted reads. The fix involves adding the READ_ONCE() macro to ensure atomic and consistent reads of this variable, preventing concurrent modification issues. This vulnerability affects the Linux kernel source versions identified by the commit hash 2100c8d2d9db23c0a09901a782bb4e3b21bee298, indicating a specific kernel tree state rather than a traditional version number. The issue is rooted in kernel-level concurrency control and impacts the TCP Fast Open feature, which is used to reduce latency in TCP connections by allowing data to be sent during the initial handshake. While no known exploits are reported in the wild, the vulnerability could theoretically lead to kernel instability or unpredictable behavior in network communications if exploited. The lack of a CVSS score suggests this is a recently disclosed issue with limited public analysis. However, the vulnerability is technical and requires kernel-level access or the ability to trigger concurrent sysctl reads and writes, which limits the attack surface to privileged or local users or processes. The patch involves kernel code changes to enforce atomic reads, a standard concurrency control practice in kernel development.

For European organizations, the impact of CVE-2022-49586 primarily concerns systems running vulnerable Linux kernel versions, especially those utilizing the TCP Fast Open feature. Potential impacts include kernel crashes, data corruption, or denial of service conditions affecting network services reliant on TCP Fast Open. This could disrupt critical infrastructure, cloud services, or enterprise applications hosted on Linux servers. Organizations with high network throughput or latency-sensitive applications might experience degraded performance or instability. Although exploitation requires local or privileged access, the vulnerability could be leveraged in multi-tenant environments, such as cloud providers or shared hosting, to affect other tenants or escalate privileges. Given the widespread use of Linux in European data centers, telecommunications, and government infrastructure, unpatched systems could face operational risks. However, the absence of known exploits and the technical complexity of triggering the race condition reduce the immediate threat level. Still, the vulnerability underscores the importance of maintaining up-to-date kernel versions to ensure network stack reliability and security.

European organizations should prioritize updating their Linux kernels to versions that include the patch for CVE-2022-49586. Specifically, kernel maintainers and system administrators should apply the fix that adds READ_ONCE() to sysctl_tcp_fastopen readers to prevent data races. For environments where immediate patching is not feasible, organizations should consider disabling TCP Fast Open temporarily to mitigate potential exploitation vectors. Additionally, implementing strict access controls to limit who can modify sysctl parameters or load kernel modules reduces the risk of local exploitation. Monitoring kernel logs for unusual TCP stack behavior or crashes can help detect attempts to trigger the vulnerability. In cloud or containerized environments, ensuring that host kernels are patched and that container runtimes do not expose privileged sysctl interfaces is critical. Finally, integrating this vulnerability into vulnerability management and patching workflows will help maintain ongoing protection.