NULL Pointer Dereference Affecting kernel6.18-tools package, versions <1:6.18.44-99.149.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.17% (7th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL618TOOLS-19814167
  • published15 Sept 2026
  • disclosed15 Aug 2026

Introduced: 15 Aug 2026

CVE-2026-74477  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.18-tools to version 1:6.18.44-99.149.amzn2023 or higher.
This issue was patched in ALAS2023-2026-2106.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.18-tools package and not the kernel6.18-tools package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

uprobes: Fix NULL pointer dereference in hprobe_expire()

Forking a task that has a pending uretprobe can oops the kernel with a NULL pointer dereference in the clone() path:

BUG: kernel NULL pointer dereference, address: 0000000000000018 Oops: 0002 [#1] SMP NOPTI RIP: 0010:hprobe_expire CR2: 0000000000000018 Call Trace: uprobe_copy_process copy_process kernel_clone __x64_sys_clone do_syscall_64 entry_SYSCALL_64_after_hwframe

This was found on real hosts on Meta fleet.

I've got the impression that this is what is happening:

CPU 1 CPU 2 (traced task)


                             hit uprobe, prepare_uretprobe():
                               hprobe LEASED, refcount &gt;= 1

uprobe_unregister() put_uprobe(): refcount -> 0 fork() -> dup_utask() hprobe_expire(hprobe, true) try_get_uprobe() -> NULL get_uprobe(NULL) <-- Oops

Only take the extra reference when the uprobe is non-NULL; a NULL means it is gone and is the correct value to return.

CVSS Base Scores

version 3.1