Bug 2507275 (CVE-2026-64351)

Summary: CVE-2026-64351 kernel: net: usb: kalmia: bound RX frame length in kalmia_rx_fixup()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's USB Kalmia driver. An attacker with a specially crafted USB device could exploit an out-of-bounds read vulnerability in the `kalmia_rx_fixup()` function. This occurs due to an incorrect calculation of the USB packet length when processing short bulk-IN frames, leading to a memory underflow. This flaw could allow an attacker to read sensitive information from outside the intended memory buffer or potentially cause a denial of service.
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Description OSIDB Bzimport 2026-07-25 10:14:04 UTC 
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.
Comment 1 TEJ RATHI 2026-07-27 05:52:48 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072518-CVE-2026-64351-eae1@gregkh/T