CVE-2026-64336 USB: serial: keyspan_pda: fix information leak

What is CVE-2026-64336?

CVE-2026-64336 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:

USB: serial: keyspan_pda: fix information leak

The write() callback is supposed to return the number of characters accepted or a negative errno. Since the addition of write fifo support the keyspan_pda implementation will however return the number characters submitted to the device if the write urb is not already in use. If this number is larger than the number of characters passed to write(), the line discipline continues writing data from beyond the tty write buffer.

Fix the information leak by making sure that keyspan_pda_write_start() returns zero on success as intended.

Weakness: CWE-401

Which versions are affected by CVE-2026-64336?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-64336?

Apply the vendor's patch.

Is CVE-2026-64336 being exploited?

There is no known exploitation of CVE-2026-64336 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-64336, DEBIAN-CVE-2026-64336, GHSA-mhg5-fr5x-3g7c, ROOT-OS-UBUNTU-2204-CVE-2026-64336, UBUNTU-CVE-2026-64336.