CVE-2025-21704

In the Linux kernel, the following vulnerability has been resolved: usb: cdc-acm: Check control transfer buffer size before access If the first fragment is shorter than struct usb_cdc_notification, we can't calculate an expected_size. Log an error and discard the notification instead of reading lengths from memory outside the received data, which can lead to memory corruption when the expected_size decreases between fragments, causing `expected_size - acm->nb_index` to wrap. This issue has been present since the beginning of git history; however, it only leads to memory corruption since commit ea2583529cd1 ("cdc-acm: reassemble fragmented notifications"). A mitigating factor is that acm_ctrl_irq() can only execute after userspace has opened /dev/ttyACM*; but if ModemManager is running, ModemManager will do that automatically depending on the USB device's vendor/product IDs and its other interfaces.

• linux linux kernel (>= 2.6.13 < 5.4.291) • linux linux kernel (>= 5.5 < 5.10.235) • linux linux kernel (>= 5.11 < 5.15.179) • linux linux kernel (>= 5.16 < 6.1.129) • linux linux kernel (>= 6.2 < 6.6.79) • linux linux kernel (>= 6.7 < 6.12.16) • linux linux kernel (>= 6.13 < 6.13.4) • linux linux kernel 2.6.12 • linux linux kernel 6.14