Access of Resource Using Incompatible Type ('Type Confusion') Affecting kernel6.18-headers package, versions <1:6.18.44-99.149.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.2% (10th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL618HEADERS-19813092
  • published15 Sept 2026
  • disclosed10 Aug 2026

Introduced: 10 Aug 2026

CVE-2026-68174  (opens in a new tab)
CWE-843  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.18-headers 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-headers package and not the kernel6.18-headers 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 union collision of module and refcnt for dynamic events

In 'struct trace_event_call', the 'module' pointer and the 'refcnt' atomic variable share the same memory space in a union. For dynamic events, the union member is 'refcnt', which acts as an active reference counter.

When a dynamic event (such as kprobe, uprobe, fprobe, eprobe, or wprobe) has a non-zero reference count (e.g. due to active event triggers or perf attachments), its 'call->module' evaluates to a small non-zero integer instead of NULL.

When filtering or setting events for a specific module (e.g., writing ':mod:<module>' to 'set_event'), the code in '__ftrace_set_clr_event_nolock()' and 'update_event_fields()' reads 'call->module' directly without checking whether the event is dynamic. This causes the kernel to treat the small integer (refcnt) as a 'struct module' pointer, leading to a NULL/invalid pointer dereference (Oops) when dereferencing the module name.

Fix this by ensuring that the 'TRACE_EVENT_FL_DYNAMIC' flag is checked before treating 'call->module' as a valid pointer in these code paths.

CVSS Base Scores

version 3.1