CVE-2026-43458: serial: caif: hold tty->link reference in ldisc_open and ser_release

Severity: high (CVSS 7.8 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: 2026-05-08 · updated 2026-06-17
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: serial: caif: hold tty->link reference in ldisc_open and ser_release A reproducer triggers a KASAN slab-use-after-free in pty_write_room() when caif_serial's TX path calls tty_write_room(). The faulting access is on tty->link->port. Hold an extra kref on tty->link for the lifetime of the caif_serial line discipline: get it in ldisc_open() and drop it in ser_release(), and also drop it on the ldisc_open() error path. With this change applied, the reproducer no longer triggers the UAF in my testing.

Affected products

Linux kernel: from 2.6.35 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.78; from 6.13 before 6.18.19 — fixed in 5.10.253, 5.15.203, 6.1.167, 6.12.78, 6.18.19, 6.19.9

How to fix

Upgrade to a fixed version: Linux kernel 5.10.253, 5.15.203, 6.1.167, 6.12.78. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-43458 or the next vulnerability affects your stack