---
id: "CVE-2026-98612"
kind: "vulnerability"
aliases: ["CVE-2026-98612"]
title: "Linux kernel: USB catc driver reads past receive buffer on crafted packets"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["catc", "kernel", "linux", "runtime", "usb"]
not_affected_if: ["default-config", "no-catc-driver"]
published_at: "2026-10-18T16:17:14+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:21:24+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98612", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel: USB catc driver reads past receive buffer on crafted packets

A crafted USB packet header makes the Linux kernel's catc network driver copy data past the end of its receive buffer, and accepts undersized frames that lead to reads of uninitialised memory. The sources do not state whether this allows code execution or only crashes and information leaks.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check whether the `catc` driver is loaded with `lsmod | grep catc` or built in with `grep CONFIG_USB_NET_CDCETHER /boot/config-$(uname -r)` (the catc driver is `CONFIG_USB_CATC`)
- Compare the running kernel with `uname -r` against the fixed kernel release listed in the upstream stable tree (unknown in the sources)

## Fix

- Update the Linux kernel to a release that includes the upstream commit 'net: usb: catc: bound the RX packet length in catc_rx_done()' (version unknown in the sources)
- Blacklist the catc module if USB CATC adapters are not used: `echo 'blacklist catc' > /etc/modprobe.d/catc.conf`

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98612

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

net: usb: catc: bound the RX packet length in catc_rx_done()

catc_rx_done() walks a multi-packet URB, reading a two-byte length from
each packet header. Its bound, pkt_len > urb->actual_length, ignores the
header offset and compares against the whole transfer rather than the
bytes left from pkt_start, so a crafted packet header makes
skb_copy_to_linear_data() read past the buffer.

A length below ETH_HLEN is also accepted, including zero, and
eth_type_trans() then reads a MAC header from the uninitialised tailroom
of a shorter skb. The is_f5u011 branch takes its length straight from
the transfer, so a zero-length URB reaches the same path.

Track the bytes remaining from the current packet, and reject a header
that does not fit, a length past what is left, and a length below an
Ethernet header.

A transfer shorter than an Ethernet header, including a zero-length one,
previously became a runt skb passed to netif_rx() and counted as
received; it is now counted in rx_length_errors and ends the walk.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_