CVE-2022-49595 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
tcp: Fix a data-race around sysctl_tcp_probe_threshold.
While reading sysctl_tcp_probe_threshold, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader.
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Analysis
by VulDB Data Team • 03/27/2025
The vulnerability identified as CVE-2022-49595 represents a critical data race condition within the Linux kernel's TCP implementation that specifically affects the sysctl_tcp_probe_threshold parameter. This issue occurs in the kernel's networking subsystem where concurrent access patterns create opportunities for inconsistent data states during read and write operations. The problem manifests when multiple kernel threads attempt to access the tcp_probe_threshold sysctl parameter simultaneously, with one thread potentially modifying the value while another reads it, leading to unpredictable behavior and potential system instability.
The technical flaw stems from the absence of proper synchronization mechanisms when accessing the sysctl_tcp_probe_threshold variable. In concurrent programming environments, data races occur when two or more threads access the same memory location concurrently, with at least one access being a write operation, and no synchronization mechanism is in place to prevent conflicts. This particular vulnerability falls under the CWE-362 category of "Concurrent Execution using Shared Resource with Improper Synchronization" and aligns with the broader class of race condition vulnerabilities that are among the most challenging to detect and exploit in kernel-level software. The Linux kernel's networking stack relies heavily on proper synchronization primitives to maintain data integrity, especially when dealing with system configuration parameters that can be modified at runtime through the sysctl interface.
The operational impact of this vulnerability extends beyond simple data corruption, as it can potentially lead to system crashes, network connectivity issues, or even provide attack vectors for privilege escalation. When the tcp_probe_threshold parameter is modified during active network operations, the inconsistent reading of this value can cause the TCP stack to make incorrect decisions regarding probe timing and network behavior. Attackers could potentially exploit this race condition to disrupt network services or cause denial of service conditions. The vulnerability affects all Linux kernel versions that implement the TCP probe threshold functionality and could be particularly problematic in high-availability environments where network stability is critical. From an ATT&CK framework perspective, this vulnerability could be leveraged in the privilege escalation and defense evasion tactics, as it allows for potential manipulation of kernel network parameters that could be used to bypass security controls or establish persistent access.
Mitigation strategies for CVE-2022-49595 involve applying the official kernel patch that introduces READ_ONCE() macro usage to protect the reader of the sysctl_tcp_probe_threshold parameter. This solution ensures that reads of the variable occur atomically without interference from concurrent writers, effectively eliminating the race condition. System administrators should prioritize updating their kernel versions to include this fix, particularly in production environments where network stability is paramount. Additional monitoring should be implemented to detect any anomalous network behavior that might indicate exploitation attempts. The patch implementation follows established kernel development practices for addressing race conditions and demonstrates the importance of proper synchronization mechanisms in kernel code. Organizations should also consider implementing network segmentation and access controls to limit potential exploitation vectors while the patch is being deployed across their infrastructure.