Linux kernel: caif_serial UAF via tty link ref in pty_write_room()
CVE-2026-43458 Published on May 8, 2026
serial: caif: hold tty->link reference in ldisc_open and ser_release
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.
Products Associated with CVE-2026-43458
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Affected Versions
Linux:- Version e31d5a05948e4478ba8396063d1e1f39880928e2 and below 23a3ac2e2262a291498567418227b99e1f3606b1 is affected.
- Version e31d5a05948e4478ba8396063d1e1f39880928e2 and below 52135420e9f75853ea0c6cea7b736e3e98495f7d is affected.
- Version e31d5a05948e4478ba8396063d1e1f39880928e2 and below ca2ceba983bb23ea0202c2882d963253416654a3 is affected.
- Version e31d5a05948e4478ba8396063d1e1f39880928e2 and below 8460187b4852fd00bd1c76394358053f3fa4d089 is affected.
- Version e31d5a05948e4478ba8396063d1e1f39880928e2 and below 27e43356d0defb9fc7fa25265219a3ffeb7b3e98 is affected.
- Version e31d5a05948e4478ba8396063d1e1f39880928e2 and below 35b58d3bc716ebb9ebd10fe1cac8c1177242511c is affected.
- Version e31d5a05948e4478ba8396063d1e1f39880928e2 and below 97a0bb491cae39478c6225381f14e9ac67b7bba7 is affected.
- Version e31d5a05948e4478ba8396063d1e1f39880928e2 and below 288598d80a068a0e9281de35bcb4ce495f189e2a is affected.
- Version 2.6.35 is affected.
- Before 2.6.35 is unaffected.
- Version 5.10.253, <= 5.10.* is unaffected.
- Version 5.15.203, <= 5.15.* is unaffected.
- Version 6.1.167, <= 6.1.* is unaffected.
- Version 6.6.130, <= 6.6.* is unaffected.
- Version 6.12.78, <= 6.12.* is unaffected.
- Version 6.18.19, <= 6.18.* is unaffected.
- Version 6.19.9, <= 6.19.* is unaffected.
- Version 7.0, <= * is unaffected.