CVE-2026-90057 slip: remove slip_hangup() to fix use-after-free in slip_receive_buf()
A race condition in the Linux kernel's SLIP driver allows a use-after-free, potentially leading to code execution or system crash.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90057?
CVE-2026-90057 is a high-severity use after free vulnerability in Linux, published on 17 Sep 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:
slip: remove slip_hangup() to fix use-after-free in slip_receive_buf()
Jaeyoung Chung and Eulgyu Kim reported a slab-use-after-free read in slip_receive_buf() when racing against tty hangup.
tty_ldisc_hangup() calls ld->ops->hangup() while holding only a read lock on tty->ldisc_sem (via tty_ldisc_ref()). Because slip_hangup() simply called slip_close(), it ran concurrently with reader functions such as slip_receive_buf().
slip_close() unregisters and frees the net device and its private struct slip, causing concurrent reader threads in slip_receive_buf() to dereference freed memory.
Line discipline close() is already guaranteed to be called under the write lock of tty->ldisc_sem during hangup processing (in tty_ldisc_reinit() or tty_ldisc_kill()).
Remove slip_hangup() so teardown is serialized cleanly by slip_close().
Which versions are affected by CVE-2026-90057?
How do I fix CVE-2026-90057?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-90057 being exploited?
There is no known exploitation of CVE-2026-90057 in the wild and no public exploit code.
Sources
Also known as AZL-102930, BELL-CVE-2026-90057, DEBIAN-CVE-2026-90057, GHSA-45fm-hw2m-668x, UBUNTU-CVE-2026-90057.