CVE-2026-99233
Received Received - Intake

Reference Count Leak in Linux Kernel Tracing Histograms

Publication date: 2026-11-02

Last updated on: 2026-11-02

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: tracing/histograms: Verify event_call identity when updating synth_event refcount In event_hist_trigger_parse() and hist_unreg_all(), the histogram registration and unregistration paths look up find_synth_event() using trace_event_name(file->event_call) and adjust se->ref if a match is found. Because find_synth_event() only compares the event basename, registering or removing a histogram on a non-synthetic trace event whose basename matches a synthetic event erroneously modifies the synthetic event's reference count. If a histogram is registered on the non-synthetic event before the synthetic event is created and removed afterwards, se->ref is decremented without a matching increment, allowing the synthetic event to be freed while an active histogram action still holds a pointer to it. Introduce find_synth_event_call() to verify that &se->call matches file->event_call before adjusting se->ref.

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Meta Information

Published
2026-11-02
Last Modified
2026-11-02
Generated
2026-11-02
AI Q&A
2026-11-02
EPSS Evaluated
N/A
NVD
CVE-2026-99233

Affected Vendors & Products

Showing 7 associated CPEs
Vendor Product Version / Range
Linux Linux 4b147936fa509650beaf638b331573c23ba4d609
Linux Linux 4b147936fa509650beaf638b331573c23ba4d609
Linux Linux 4b147936fa509650beaf638b331573c23ba4d609
Linux Linux 4b147936fa509650beaf638b331573c23ba4d609
Linux Linux 4b147936fa509650beaf638b331573c23ba4d609
Linux Linux 4b147936fa509650beaf638b331573c23ba4d609
Linux Linux 4.17

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability where histogram registration or unregistration on a non-synthetic trace event with a matching basename can incorrectly modify the reference count of a synthetic event. This leads to a synthetic event being freed while an active histogram action still holds a pointer to it.

Detection Guidance

This vulnerability is specific to the Linux kernel and requires kernel-level inspection. Detection involves checking kernel logs for trace event mismatches or synthetic event reference count issues. Use commands like dmesg | grep -i trace or journalctl -k | grep -i synth to review kernel logs for suspicious events. No direct network detection commands are applicable.

Impact Analysis

An attacker with local access could exploit this to cause a denial of service or potentially execute arbitrary code in the kernel context. The high impact includes confidentiality, integrity, and availability risks due to the CVSS score of 7.8.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR or HIPAA as it is a Linux kernel issue related to trace event handling. However, if exploited, it could lead to system instability or crashes, potentially impacting systems handling sensitive data subject to these regulations.

Mitigation Strategies

Immediately update the Linux kernel to the latest patched version provided by your distribution. Avoid manual workarounds as they may not fully address the issue. Monitor kernel logs for trace event errors post-update to confirm resolution.

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