CVE-2025-22101 in Linux
Summary
by MITRE • 04/16/2025
In the Linux kernel, the following vulnerability has been resolved:
net: libwx: fix Tx L4 checksum
The hardware only supports L4 checksum offload for TCP/UDP/SCTP protocol. There was a bug to set Tx checksum flag for the other protocol that results in Tx ring hang. Fix to compute software checksum for these packets.
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Analysis
by VulDB Data Team • 02/15/2026
This vulnerability resides within the Linux kernel's networking stack, specifically affecting the libwx network driver component that handles packet transmission operations. The issue manifests as a critical flaw in how the kernel manages hardware checksum offloading for outgoing network packets. The vulnerability stems from an improper handling of checksum flags when processing different protocol types beyond the supported TCP/UDP/SCTP protocols. When the kernel encounters packets using unsupported protocols, it incorrectly sets the hardware checksum offload flags, leading to a complete transmission ring hang that prevents further packet processing. This represents a significant reliability issue that can result in network service disruption and potential denial of service conditions for systems relying on affected network drivers.
The technical root cause of this vulnerability can be categorized under CWE-129 Input Validation and CWE-787 Out-of-bounds Write, as the kernel fails to properly validate protocol types before applying hardware offloading flags. The flaw occurs during the packet transmission path where the system attempts to leverage hardware acceleration for checksum computation but lacks proper protocol validation logic. The vulnerability specifically impacts the transmit ring management within the network driver, where the incorrect flag setting causes the hardware to enter an undefined state that results in a complete hang condition. This issue directly violates the expected behavior of network hardware offloading mechanisms and demonstrates a critical failure in protocol handling within the kernel's networking subsystem.
From an operational perspective, this vulnerability creates a severe reliability risk for systems utilizing the affected network drivers, particularly in high-throughput environments where network performance and availability are critical. The transmission ring hang condition effectively renders the network interface unusable until system reboot or manual intervention occurs, potentially leading to extended service outages and significant operational impact. Network administrators may observe complete loss of network connectivity for affected interfaces, with no immediate indication of the underlying hardware offloading issue. The vulnerability affects systems running Linux kernel versions that include the problematic libwx driver implementation, with the risk increasing in environments handling diverse protocol traffic patterns that might trigger the faulty code path.
Mitigation strategies should focus on immediate kernel updates that include the patched version resolving the Tx L4 checksum handling issue. Organizations should prioritize applying the relevant kernel security patches to prevent exploitation of this vulnerability. Alternative approaches include disabling hardware checksum offloading for affected network interfaces through kernel parameters or driver configuration settings, though this may impact network performance. Network monitoring should be enhanced to detect potential transmission ring hang conditions, and system administrators should implement automated alerting for network interface failures. The fix implemented addresses the core issue by ensuring that software checksum computation is properly utilized for unsupported protocols, preventing the hardware state corruption that leads to ring hangs. This remediation aligns with security best practices for kernel-level network driver stability and follows established protocols for addressing hardware offloading vulnerabilities in operating system networking stacks.