CVE-2026-64351 net: usb: kalmia: bound RX frame length in kalmia_rx_fixup()
A malicious USB device can trigger an integer underflow in the kalmia driver, leading to out-of-bounds reads and potential system crashes.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64351?
CVE-2026-64351 is a medium-severity vulnerability in Linux kernel, published on 25 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net: usb: kalmia: bound RX frame length in kalmia_rx_fixup()
kalmia_rx_fixup() computes usb_packet_length = skb->len - (2 * KALMIA_HEADER_LENGTH) as a u16, guarded only by a pre-loop check that skb->len is at least KALMIA_HEADER_LENGTH, which is 6. A device can deliver a short bulk-IN frame with skb->len in the 6 to 11 range, or leave a short trailing remainder on a later loop iteration. Either case underflows usb_packet_length to about 65530.
That bypasses the usb_packet_length < ether_packet_length truncation path. The device-supplied ether_packet_length, a le16 up to 65535 read from header_start[2], then drives a memcmp() and the following skb_trim() and skb_pull() past the end of the rx buffer. The rx buffer is hard_mtu * 10, which is 14000 bytes. That is an out of bounds read.
Require both the start and end framing headers to be present before subtracting them, on every loop iteration.
Which versions are affected by CVE-2026-64351?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64351?
Apply the vendor's patch.
Is CVE-2026-64351 being exploited?
There is no known exploitation of CVE-2026-64351 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-93683, BELL-CVE-2026-64351, DEBIAN-CVE-2026-64351, GHSA-8qc4-xrrp-xx3v, ROOT-OS-UBUNTU-2204-CVE-2026-64351, UBUNTU-CVE-2026-64351.