NULL Pointer Dereference Affecting python3-perf6.12-debuginfo package, versions <1:6.12.113-138.209.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.17% (7th percentile)

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  • Snyk IDSNYK-AMZN2023-PYTHON3PERF612DEBUGINFO-21812171
  • published29 Oct 2026
  • disclosed23 Oct 2026

Introduced: 23 Oct 2026

NewCVE-2026-98979  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 python3-perf6.12-debuginfo to version 1:6.12.113-138.209.amzn2023 or higher.
This issue was patched in ALAS2023-2026-3335.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python3-perf6.12-debuginfo package and not the python3-perf6.12-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:

namespace: refuse an automount below a mount that is in no namespace

It's possible to add autmounts even when the parent mount isn't in the mount namespace of the caller. The only requirement we have is that the parent mount namespace must not be NULL, i.e., unmounted.

Problem is that clone_private_mount() has MNT_NS_INTERNAL which makes that trivially true. So that passes the test and attach_recursive_mnt() accepts that as a mount point and funny enough, count_mounts() dereferences MNT_NS_INTERNAL. The problem is it is an error pointer...

So we can reach this in userspace via fanotify. A filesystem mark on the lower filesystem of an overlay reports paths on the layer clone and reading the event hands out a descriptor on it. For example with debugfs as the lower layer it goes kaboom:

openat(evfd, "tracing", O_DIRECTORY)

Oops: general protection fault KASAN: null-ptr-deref in range [0x1d0-0x1d7] RIP: 0010:count_mounts+0x35/0x200 attach_recursive_mnt finish_automount

And since that sleeping beauty happens under namespace_sem held for writing every mount operation on the system blocks from then on. Congrats.

Use is_mounted() instead which rejects unmounted and internal mounts alike. The open fails with EINVAL just as it did before clone_private_mount() used MNT_NS_INTERNAL.

CVSS Base Scores

version 3.1