CVE-2026-53385 vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write

What is CVE-2026-53385?

CVE-2026-53385 is a medium-severity vulnerability in Linux kernel, published on 19 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:

vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write

A KASAN null-ptr-deref was observed in vcs_notifier():

BUG: KASAN: null-ptr-deref in vcs_notifier+0x98/0x130 Read of size 2 at addr qmp_cmd_name: qmp_capabilities, arguments: {}

The issue is a race condition in vcs_write(). When the console_lock is temporarily dropped (to copy data from userspace), the vc_data pointer obtained from vcs_vc() may become stale. After re-acquiring the lock, vcs_vc() is called again to re-validate the pointer. If the vc has been deallocated in the meantime, vcs_vc() returns NULL, and the while loop breaks (with written > 0). However, after the loop, vcs_scr_updated(vc) is still called with the now-NULL vc pointer, leading to a null pointer dereference in the notifier chain (vcs_notifier dereferences param->vc).

Fix this by adding a NULL check for vc before calling vcs_scr_updated().

Weakness: CWE-476

Which versions are affected by CVE-2026-53385?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-53385?

Apply the vendor's patch.

Is CVE-2026-53385 being exploited?

There is no known exploitation of CVE-2026-53385 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-2026-53385, DEBIAN-CVE-2026-53385, GHSA-3f5p-6w75-ppf6, ROOT-OS-UBUNTU-2204-CVE-2026-53385, UBUNTU-CVE-2026-53385.