Use After Free Affecting perf6.18-debuginfo package, versions <1:6.18.56-126.188.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.16% (5th percentile)

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  • Snyk IDSNYK-AMZN2023-PERF618DEBUGINFO-22394022
  • published10 Nov 2026
  • disclosed18 Oct 2026

Introduced: 18 Oct 2026

NewCVE-2026-98788  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 perf6.18-debuginfo to version 1:6.18.56-126.188.amzn2023 or higher.
This issue was patched in ALAS2023-2026-3390.

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:

futex: Fix private hash use-after-free on resize

poll_state_synchronize_rcu(mm->futex.phash.batches) is used by futex_ref_drop() to check that a grace period has passed since the current hash was published. This relies on batches referencing a grace period which started after the hash pointer was assigned.

__futex_pivot_hash() sets mmph->batches before it replaces mmph->hash:

scoped_guard(rcu) {
        mmph-&gt;batches = get_state_synchronize_rcu();
        rcu_assign_pointer(mmph-&gt;hash, new);
}

The scoped_guard(rcu) doesn't stop new grace periods from starting, and if one starts between those two assignments, futex_ref_drop() can move forward while a reader still holds a pointer to the old hash.

Fix things by setting mmph->batches after assigning mmph->hash. The scoped_guard(rcu) isn't needed, so let's drop that as well.

CVSS Base Scores

version 3.1