Expired Pointer Dereference Affecting perf6.18-debuginfo package, versions <1:6.18.51-120.162.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.12% (2nd percentile)

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  • Snyk IDSNYK-AMZN2023-PERF618DEBUGINFO-20854250
  • published13 Oct 2026
  • disclosed11 Sept 2026

Introduced: 11 Sep 2026

CVE-2026-89600  (opens in a new tab)
CWE-825  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 perf6.18-debuginfo to version 1:6.18.51-120.162.amzn2023 or higher.
This issue was patched in ALAS2023-2026-3187.

NVD Description

Note: Versions mentioned in the description apply only to the upstream perf6.18-debuginfo package and not the perf6.18-debuginfo 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:

fanotify: fix use-after-free of file range info

fsnotify_pre_content() builds its file_range on the triggering task's stack. fanotify_alloc_perm_event() saves a pointer to range.pos in the heap-allocated permission event so copy_range_info_to_user() can report the offset later.

The event reader can set the event state to FAN_EVENT_REPORTED and then sleep while preparing the file descriptor. If a signal interrupts the triggering task at that point, fanotify_get_response() changes the state to FAN_EVENT_CANCELED and returns. This unwinds the file_range stack frame while the reader still owns the event. The reader then dereferences pevent->ppos and copies the stale stack value to userspace.

KASAN reported:

BUG: KASAN: use-after-free in fanotify_read+0x293e/0x2970 Read of size 8 at addr ffff88811434fc50 by task fanotify_inotif/95 Call Trace: fanotify_read+0x293e/0x2970 vfs_read+0x177/0xa20 ksys_read+0xf7/0x1c0 do_syscall_64+0xf9/0x540 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Store the range position directly in the permission event and use FANOTIFY_NO_RANGE when range information is unavailable. The event remains alive until the reader finishes, so the reported offset no longer depends on the triggering task's stack.

CVSS Base Scores

version 3.1