CVE-2026-53194: Linux kernel · USB: serial: kl5kusb105: fix bulk-out buffer overflow
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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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
- git.kernel.org/stable/c/60af1fd82983c26604102e63a3fcc822c186cceb (opens in a new tab)
- git.kernel.org/stable/c/0a57320f71941d4e0b1307453c9a1f0939afe666 (opens in a new tab)
- git.kernel.org/stable/c/14147b7963685957839c76ba8094924e22777d79 (opens in a new tab)
- git.kernel.org/stable/c/a1288cd700f721c1a119c4f1e8efa234e59caada (opens in a new tab)
- git.kernel.org/stable/c/70d86e355c564b5510fde61361df014f5476c83e (opens in a new tab)
- git.kernel.org/stable/c/372f33ebed747d91870f57c0a2e62884a870bffa (opens in a new tab)
- git.kernel.org/stable/c/bde742b076cbe26ecc89c8c68c76ae076a524d02 (opens in a new tab)
- git.kernel.org/stable/c/96d47e40bf9db4a9efd5c8fb53287a508d165f14 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-53194 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2492703 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53194.json (opens in a new tab)