CVE-2026-68174
tracing: Fix union collision of module and refcnt for dynamic events
Description
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.
INFO
Published Date :
Aug. 10, 2026, 1:20 p.m.
Last Modified :
Aug. 17, 2026, 5:18 a.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Check TRACE_EVENT_FL_DYNAMIC flag before accessing call->module.
- Ensure correct handling of dynamic events.
- Apply the kernel patch to resolve the issue.
References to Advisories, Solutions, and Tools
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specific instances of vulnerabilities, CWE categorizes the common flaws or
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associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
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stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-68174
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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CVE-2026-68174 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-68174 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 17, 2026
Action Type Old Value New Value Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '4c86bc531e60900053384867c082675bba82c29f', 'lessThan': 'b6a4575f22925da7e6aa00171e9fc0e5029c0bc9', 'versionType': 'git'}, {'status': 'affected', 'version': '4c86bc531e60900053384867c082675bba82c29f', 'lessThan': '43a23dfe0024afd3d2b0232e987d0292919a9b24', 'versionType': 'git'}, {'status': 'affected', 'version': '4c86bc531e60900053384867c082675bba82c29f', 'lessThan': 'b4eb07bde606c2096b24252be589e735eff6d413', 'versionType': 'git'}], 'programFiles': ['kernel/trace/trace_events.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.14'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.14', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.18.42', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc5', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['kernel/trace/trace_events.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '4c86bc531e60900053384867c082675bba82c29f', 'lessThan': 'b6a4575f22925da7e6aa00171e9fc0e5029c0bc9', 'versionType': 'git'}, {'status': 'affected', 'version': '4c86bc531e60900053384867c082675bba82c29f', 'lessThan': '43a23dfe0024afd3d2b0232e987d0292919a9b24', 'versionType': 'git'}, {'status': 'affected', 'version': '4c86bc531e60900053384867c082675bba82c29f', 'lessThan': 'b4eb07bde606c2096b24252be589e735eff6d413', 'versionType': 'git'}], 'programFiles': ['kernel/trace/trace_events.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.14'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.14', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.18.42', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['kernel/trace/trace_events.c'], 'defaultStatus': 'affected'}] -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 10, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '4c86bc531e60900053384867c082675bba82c29f', 'lessThan': 'b6a4575f22925da7e6aa00171e9fc0e5029c0bc9', 'versionType': 'git'}, {'status': 'affected', 'version': '4c86bc531e60900053384867c082675bba82c29f', 'lessThan': '43a23dfe0024afd3d2b0232e987d0292919a9b24', 'versionType': 'git'}, {'status': 'affected', 'version': '4c86bc531e60900053384867c082675bba82c29f', 'lessThan': 'b4eb07bde606c2096b24252be589e735eff6d413', 'versionType': 'git'}], 'programFiles': ['kernel/trace/trace_events.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.14'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.14', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.18.42', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc5', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['kernel/trace/trace_events.c'], 'defaultStatus': 'affected'}] Added Description 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. Added Reference https://git.kernel.org/stable/c/43a23dfe0024afd3d2b0232e987d0292919a9b24 Added Reference https://git.kernel.org/stable/c/b4eb07bde606c2096b24252be589e735eff6d413 Added Reference https://git.kernel.org/stable/c/b6a4575f22925da7e6aa00171e9fc0e5029c0bc9