Improper Update of Reference Count Affecting kernel6.18-libbpf-debuginfo package, versions <1:6.18.20-20.229.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.02% (5th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL618LIBBPFDEBUGINFO-16349617
  • published3 May 2026
  • disclosed25 Mar 2026

Introduced: 25 Mar 2026

CVE-2026-23380  (opens in a new tab)
CWE-911  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.18-libbpf-debuginfo to version 1:6.18.20-20.229.amzn2023 or higher.
This issue was patched in ALAS2023-2026-1596.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.18-libbpf-debuginfo package and not the kernel6.18-libbpf-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:

tracing: Fix WARN_ON in tracing_buffers_mmap_close

When a process forks, the child process copies the parent's VMAs but the user_mapped reference count is not incremented. As a result, when both the parent and child processes exit, tracing_buffers_mmap_close() is called twice. On the second call, user_mapped is already 0, causing the function to return -ENODEV and triggering a WARN_ON.

Normally, this isn't an issue as the memory is mapped with VM_DONTCOPY set. But this is only a hint, and the application can call madvise(MADVISE_DOFORK) which resets the VM_DONTCOPY flag. When the application does that, it can trigger this issue on fork.

Fix it by incrementing the user_mapped reference count without re-mapping the pages in the VMA's open callback.

CVSS Base Scores

version 3.1