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Response snapshot Nov 2, 2026, 17:11 UTC

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VulnerabilityCVE-2026-99233

Linux kernel: tracing/histograms: Verify event_call identity when updating synth_event refcount

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.

At a glance

Exploited
Not known
Severity
7.8 High (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-99233 (opens a new tab)

What happened

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.

Continue reading

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.

Scores and how they were measured

CVSS base severity

7.8

Version 3.1As of

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-99233 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, November 2). Linux kernel: tracing/histograms: Verify event_call identity when updating synth_event refcount (CVE-2026-99233). https://kevwire.com/record/CVE-2026-99233

MLA

"Linux kernel: tracing/histograms: Verify event_call identity when updating synth_event refcount (CVE-2026-99233)." KEVWire, 2 Nov. 2026, kevwire.com/record/CVE-2026-99233.

Chicago

KEVWire. "Linux kernel: tracing/histograms: Verify event_call identity when updating synth_event refcount (CVE-2026-99233)." Last modified November 2, 2026. https://kevwire.com/record/CVE-2026-99233.

Evidence summary (plain text)

Linux kernel: tracing/histograms: Verify event_call identity when updating synth_event refcount (Nov 2, 2026).
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.
CVSS 7.8 (version 3.1; evidence as of Nov 2, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-99233).
Sources:
NVD CVE-2026-99233: https://nvd.nist.gov/vuln/detail/CVE-2026-99233
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-02T15:36:06.356Z&lastModEndDate=2026-11-02T17:10:56.063Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-11-02T15:01:12.608Z&lastModEndDate=2026-11-02T16:35:57.586Z&resultsPerPage=500&startIndex=500
Record ID: CVE-2026-99233.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Nov 2, 2026, 17:10 UTC. Ingestion is not an independent editorial investigation.

NVD status: Received. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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