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

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-25 · updated 2026-09-14
Weakness: CWE-401

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.

Affected products

Linux kernel: from 5.11 before 5.15.212; from 5.16 before 6.1.178; from 6.2 before 6.6.145; from 6.7 before 6.12.96; from 6.13 before 6.18.39; from 6.19 before 7.1.4 — fixed in 5.15.212, 6.1.178, 6.12.96, 6.18.39, 6.6.145, 7.1.4

How to fix

Upgrade to a fixed version: Linux kernel 5.15.212, 6.1.178, 6.12.96, 6.18.39. Check the vendor advisory for mitigations.

References

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