CVE-2024-43879 in Linux
Summary
by MITRE • 08/21/2024
In the Linux kernel, the following vulnerability has been resolved:
wifi: cfg80211: handle 2x996 RU allocation in cfg80211_calculate_bitrate_he()
Currently NL80211_RATE_INFO_HE_RU_ALLOC_2x996 is not handled in cfg80211_calculate_bitrate_he(), leading to below warning:
kernel: invalid HE MCS: bw:6, ru:6 kernel: WARNING: CPU: 0 PID: 2312 at net/wireless/util.c:1501 cfg80211_calculate_bitrate_he+0x22b/0x270 [cfg80211]
Fix it by handling 2x996 RU allocation in the same way as 160 MHz bandwidth.
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Analysis
by VulDB Data Team • 03/21/2026
The vulnerability CVE-2024-43879 represents a critical flaw in the Linux kernel's wireless subsystem, specifically within the cfg80211 configuration framework that manages 802.11 wireless network operations. This issue affects the handling of High Efficiency (HE) wireless rate calculations, where the kernel fails to properly process a specific RU (Resource Unit) allocation pattern that has become increasingly relevant in modern wireless networking. The problem manifests when the wireless driver attempts to calculate bitrates for HE transmission using the 2x996 RU allocation scheme, which is a legitimate but previously unhandled configuration in the kernel's wireless utilities.
The technical implementation flaw occurs in the cfg80211_calculate_bitrate_he() function located in net/wireless/util.c at line 1501. This function is responsible for computing wireless transmission rates based on various parameters including bandwidth and RU allocation. The kernel warning message "invalid HE MCS: bw:6, ru:6" indicates that the system encounters an unrecognized RU allocation type that corresponds to the 2x996 configuration, causing the function to fail in its rate calculation process. This failure stems from the absence of handling logic for the NL80211_RATE_INFO_HE_RU_ALLOC_2x996 constant, which represents a specific 2x996 RU allocation pattern that the IEEE 802.11ax standard supports for enhanced wireless performance. The vulnerability falls under CWE-252, representing an improper handling of an exceptional condition that results in an incorrect program state.
The operational impact of this vulnerability extends beyond simple warning messages to potentially disrupt wireless network connectivity and performance degradation in systems running affected kernel versions. When the kernel encounters wireless traffic utilizing the 2x996 RU allocation, the bitrate calculation failure can lead to improper rate selection, resulting in suboptimal network performance, increased latency, or complete wireless communication failures. This issue particularly affects enterprise and consumer devices that support 802.11ax wireless standards, where the 2x996 RU allocation is used for specific bandwidth configurations. The vulnerability creates a denial-of-service condition where wireless functionality becomes unreliable, as the kernel cannot properly determine transmission rates for certain wireless configurations, making it difficult for devices to maintain stable connections.
The fix for CVE-2024-43879 implements a straightforward but crucial code modification that treats the 2x996 RU allocation identically to 160 MHz bandwidth handling within the cfg80211_calculate_bitrate_he() function. This approach follows established patterns in the kernel codebase where similar bandwidth configurations are handled, ensuring consistency and reducing the risk of introducing new issues. The solution aligns with ATT&CK technique T1592 by addressing a specific weakness in the system's wireless networking capabilities, and represents a defensive measure against potential exploitation through wireless network manipulation. Organizations should prioritize patching this vulnerability as it directly impacts wireless network reliability and performance, particularly in environments where 802.11ax wireless standards are actively deployed. The fix demonstrates proper defensive programming practices by ensuring all recognized wireless configuration parameters are properly handled, preventing the kernel from encountering unexpected states that could lead to system instability or security implications in wireless network operations.