CVE-2022-50877 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
net: broadcom: bcm4908_enet: update TX stats after actual transmission
Queueing packets doesn't guarantee their transmission. Update TX stats after hardware confirms consuming submitted data.
This also fixes a possible race and NULL dereference. bcm4908_enet_start_xmit() could try to access skb after freeing it in the bcm4908_enet_poll_tx().
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Analysis
by VulDB Data Team • 04/26/2026
The CVE-2022-50877 vulnerability resides within the Linux kernel's networking subsystem, specifically affecting the Broadcom bcm4908 ethernet driver implementation. This issue manifests as a timing discrepancy in how transmit statistics are updated within the network driver's packet processing pipeline. The vulnerability stems from the driver's improper handling of packet transmission state updates, where transmit statistics are incremented before the actual hardware transmission occurs rather than after confirming successful data consumption by the network hardware.
The technical flaw represents a classic race condition scenario that violates proper driver state management principles. In the bcm4908_enet_start_xmit() function, packets are queued for transmission but the transmit statistics are updated immediately upon queuing rather than after hardware confirmation. This creates a dangerous window where the driver may attempt to access packet data structures that have already been freed during the cleanup process in bcm4908_enet_poll_tx(). The underlying issue demonstrates poor adherence to kernel networking driver development best practices and proper resource lifecycle management as outlined in the Linux kernel documentation and security guidelines.
The operational impact of this vulnerability extends beyond simple statistical inaccuracies to potentially critical system stability concerns. The race condition can lead to NULL pointer dereferences when the driver attempts to access freed packet structures, resulting in kernel panics and system crashes that compromise availability. This represents a direct threat to network service continuity and system reliability, particularly in embedded systems or network appliances that rely heavily on the bcm4908 ethernet controller. The vulnerability affects systems using Broadcom's bcm4908 ethernet hardware where the driver fails to properly synchronize transmit state updates with actual hardware completion signals, creating an exploitable condition that could be leveraged for denial-of-service attacks.
This vulnerability aligns with CWE-362, which addresses race conditions in concurrent programming, and demonstrates characteristics consistent with ATT&CK technique T1499.004 for network denial-of-service attacks. The fix implements proper synchronization by updating transmit statistics only after hardware confirmation of data consumption, ensuring that packet structures remain valid during the entire transmission lifecycle. Mitigation strategies should include immediate kernel updates to the patched version that resolves the timing discrepancy, along with comprehensive monitoring for system stability indicators and network connectivity issues that may indicate exploitation attempts. System administrators should prioritize patch deployment across all affected platforms, particularly in mission-critical environments where network availability is paramount, and implement proper logging to detect potential exploitation attempts targeting this specific driver vulnerability.