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VulnerabilityPublished Updated

CVE-2026-53194: Linux kernel · USB: serial: kl5kusb105: fix bulk-out buffer overflow

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in bde742b076cbe26ecc89c8c68c76ae076a524d02 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in bde742b076cbe26ecc89c8c68c76ae076a524d02, a1288cd700f721c1a119c4f1e8efa234e59caada, 14147b7963685957839c76ba8094924e22777d79 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 60b3013cdaf3fa8a17243ca46b19db3cbe08d943, < bde742b076cbe26ecc89c8c68c76ae076a524d02
Fixed in
  • bde742b076cbe26ecc89c8c68c76ae076a524d02
LinuxLinuxAffected
  • ≥ 60b3013cdaf3fa8a17243ca46b19db3cbe08d943, < a1288cd700f721c1a119c4f1e8efa234e59caada
Fixed in
  • a1288cd700f721c1a119c4f1e8efa234e59caada
LinuxLinuxAffected
  • ≥ 60b3013cdaf3fa8a17243ca46b19db3cbe08d943, < 14147b7963685957839c76ba8094924e22777d79
Fixed in
  • 14147b7963685957839c76ba8094924e22777d79
LinuxLinuxAffected
  • ≥ 60b3013cdaf3fa8a17243ca46b19db3cbe08d943, < 372f33ebed747d91870f57c0a2e62884a870bffa
Fixed in
  • 372f33ebed747d91870f57c0a2e62884a870bffa
LinuxLinuxAffected
  • ≥ 60b3013cdaf3fa8a17243ca46b19db3cbe08d943, < 96d47e40bf9db4a9efd5c8fb53287a508d165f14
Fixed in
  • 96d47e40bf9db4a9efd5c8fb53287a508d165f14
LinuxLinuxAffected
  • ≥ 60b3013cdaf3fa8a17243ca46b19db3cbe08d943, < 70d86e355c564b5510fde61361df014f5476c83e
Fixed in
  • 70d86e355c564b5510fde61361df014f5476c83e

Description

In the Linux kernel, the following vulnerability has been resolved: USB: serial: kl5kusb105: fix bulk-out buffer overflow klsi_105_prepare_write_buffer() is called by the generic write path with the bulk-out buffer and its size (bulk_out_size, 64 bytes). It stores a two-byte length header at the start of the buffer and copies the payload from the write fifo starting at buf + KLSI_HDR_LEN, but passes the full buffer size as the number of bytes to copy: count = kfifo_out_locked(&port->write_fifo, buf + KLSI_HDR_LEN, size, &port->lock); When the fifo holds at least size bytes, size bytes are copied starting two bytes into the size-byte buffer, writing KLSI_HDR_LEN bytes past its end. Copy at most size - KLSI_HDR_LEN bytes instead, leaving room for the header as safe_serial already does. Writing bulk_out_size or more bytes to the tty triggers a slab out-of-bounds write, observed with KASAN by emulating the device with dummy_hcd and raw-gadget: BUG: KASAN: slab-out-of-bounds in kfifo_copy_out+0x83/0xc0 Write of size 64 at addr ffff888112c62202 by task python3 kfifo_copy_out klsi_105_prepare_write_buffer [kl5kusb105] usb_serial_generic_write_start [usbserial] Allocated by task 139: usb_serial_probe [usbserial] The buggy address is located 2 bytes inside of allocated 64-byte region The out-of-bounds write no longer occurs with this change applied.

References

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