CVE-2025-38157 in Linux
Summary
by MITRE • 07/03/2025
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath9k_htc: Abort software beacon handling if disabled
A malicious USB device can send a WMI_SWBA_EVENTID event from an ath9k_htc-managed device before beaconing has been enabled. This causes a device-by-zero error in the driver, leading to either a crash or an out of bounds read.
Prevent this by aborting the handling in ath9k_htc_swba() if beacons are not enabled.
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Analysis
by VulDB Data Team • 04/18/2026
The vulnerability CVE-2025-38157 resides within the linux kernel's wireless networking subsystem, specifically affecting the ath9k_htc driver implementation. This flaw manifests in the handling of software beacon events through the WMI_SWBA_EVENTID mechanism, creating a critical security risk that can be exploited through malicious USB devices. The issue occurs when a compromised wireless device attempts to communicate with a system running the affected kernel version, exploiting a timing window where beacon functionality has not yet been properly initialized.
The technical root cause involves a race condition within the ath9k_htc_swba() function that processes software beacon events. When a malicious USB device sends a WMI_SWBA_EVENTID event before the beaconing mechanism has been enabled, the driver fails to validate the beacon state before processing the event. This validation gap results in a division by zero error, which can manifest as either a kernel crash or more insidiously, an out-of-bounds memory read operation. The vulnerability directly maps to CWE-369, which categorizes improper handling of division by zero conditions, and CWE-129, addressing issues with insufficient bounds checking in array accesses.
The operational impact of this vulnerability extends beyond simple system crashes, as it enables potential privilege escalation and denial of service attacks. An attacker with physical access to a system running vulnerable kernel versions can exploit this flaw to cause system instability or potentially execute arbitrary code within kernel space. The attack vector requires only the presence of a malicious USB device, making it particularly dangerous in environments where untrusted USB devices might be connected, such as public computing facilities, corporate workstations, or mobile devices. This vulnerability aligns with ATT&CK technique T1059.007, which covers kernel-mode rootkits, and T1566.001, covering spearphishing attachments, though in this case the attack is delivered through physical USB media rather than network-based payloads.
Mitigation strategies should focus on immediate kernel updates to versions containing the fix, which properly validates beacon state before processing software beacon events. System administrators should implement USB device whitelisting policies to prevent unauthorized devices from connecting to critical systems. Additional protective measures include enabling kernel lockdown modes and implementing proper USB device authorization procedures. The fix implemented in the kernel resolves the issue by adding a simple validation check within the ath9k_htc_swba() function to abort processing when beacons are not enabled, preventing the erroneous division by zero condition from occurring. Organizations should also consider deploying network monitoring solutions to detect anomalous USB device behavior and implement security awareness training to reduce the risk of accidental device insertion by unauthorized personnel.