CVE Catalog

CVE-2026-68174

Low risk· EPSS 10%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.20%

10th percentile - higher than 10% of all known CVEs

Summary

In the Linux kernel tracing subsystem, there is a union collision between the module pointer and refcnt in struct trace_event_call for dynamic events. When refcnt is non-zero, the module field is interpreted as a pointer, leading to invalid pointer dereference during event filtering. The fix checks the TRACE_EVENT_FL_DYNAMIC flag before using the module field.

Risk Assessment

The risk includes kernel Oops during event configuration for a specific module, potentially leading to instability or privilege escalation.

Recommendation

Update the Linux kernel to a version with the fix that prevents invalid pointer dereference in dynamic events.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS