CVE-2025-68307 in Linux
Summary
by MITRE • 12/16/2025
In the Linux kernel, the following vulnerability has been resolved:
can: gs_usb: gs_usb_xmit_callback(): fix handling of failed transmitted URBs
The driver lacks the cleanup of failed transfers of URBs. This reduces the number of available URBs per error by 1. This leads to reduced performance and ultimately to a complete stop of the transmission.
If the sending of a bulk URB fails do proper cleanup: - increase netdev stats - mark the echo_sbk as free - free the driver's context and do accounting - wake the send queue
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Analysis
by VulDB Data Team • 03/18/2026
The vulnerability identified as CVE-2025-68307 resides within the Linux kernel's can gs_usb driver, specifically in the gs_usb_xmit_callback() function responsible for handling USB bulk transfer operations. This flaw represents a classic resource management issue where failed USB Request Blocks (URBs) are not properly cleaned up after transmission failures. The gs_usb driver facilitates communication with USB-based CAN (Controller Area Network) devices, commonly used in automotive and industrial automation systems for real-time data exchange between embedded components. When URBs fail during transmission, the driver's current implementation fails to release associated resources, creating a gradual depletion of available URBs that are essential for maintaining continuous communication. This issue directly impacts the driver's ability to handle subsequent transmission requests, ultimately leading to complete transmission stoppage.
The technical implementation flaw manifests in the driver's failure to execute proper cleanup procedures when bulk URB transmission encounters errors. According to the vulnerability resolution, the driver must properly handle failed transfers by incrementing network device statistics to track transmission failures, marking the echo_skb (socket buffer) as free to allow reuse, freeing the driver's internal context structures, and performing proper accounting to maintain resource tracking. Additionally, the driver must wake the send queue to ensure that pending transmissions can resume once resources become available. This cleanup process is critical because URBs are limited system resources that must be managed carefully to maintain driver stability and performance. The missing cleanup operations create a resource leak scenario where each failed transmission consumes one available URB without proper release, leading to progressive resource exhaustion.
The operational impact of this vulnerability extends beyond simple performance degradation to complete system failure in critical applications. In automotive systems, industrial control networks, or any environment relying on real-time CAN communication, the complete stoppage of transmission can result in catastrophic failures. The reduced performance initially manifests as delayed message delivery or increased latency, but eventually leads to complete communication breakdown. This vulnerability affects systems where USB-based CAN interfaces are utilized for safety-critical operations, potentially compromising vehicle safety systems, industrial process control, or emergency response networks. The timing and severity of impact depend on the frequency of transmission attempts and the rate at which failed URBs accumulate, making this vulnerability particularly dangerous in high-throughput environments where continuous communication is essential.
Mitigation strategies for CVE-2025-68307 require immediate patch application to the Linux kernel, specifically targeting the gs_usb driver's gs_usb_xmit_callback() function. System administrators should prioritize updating kernel versions that contain the fix, particularly in production environments where CAN communication reliability is critical. The patch implementation ensures proper resource cleanup during transmission failures by incorporating the required cleanup steps mentioned in the vulnerability description. Organizations should also implement monitoring systems to track network device statistics and detect unusual patterns in transmission failures that might indicate resource exhaustion. Additionally, implementing redundant communication paths or alternative transmission methods can provide failover capabilities when the affected driver encounters resource depletion. This vulnerability aligns with CWE-404, Resource Leak, and represents a specific instance of improper resource management in kernel drivers, which can be mapped to ATT&CK technique T1499.004 for resource depletion attacks that target system stability through resource exhaustion.