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Response snapshot Oct 26, 2026, 21:58 UTC

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VulnerabilityCVE-2026-58098

When semop(2) blocks waiting for a semaphore condition, it releases the per-set lock and sleeps.

When semop(2) blocks waiting for a semaphore condition, it releases the per-set lock and sleeps. Upon waking, it checks the sequence number embedded in the semaphore set's IPC identifier to detect whether the set was removed while the caller was asleep. This sequence number is only 15 bits wide.

At a glance

Exploited
Not known
Severity
8.4 High (CVSS 3.1)
Chance of exploitation
0.1% in the next 30 days
Sources
2 independent sources

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-58098 (opens a new tab)

What happened

When semop(2) blocks waiting for a semaphore condition, it releases the per-set lock and sleeps. Upon waking, it checks the sequence number embedded in the semaphore set's IPC identifier to detect whether the set was removed while the caller was asleep. This sequence number is only 15 bits wide.

If enough semaphore sets are created and destroyed in the same table slot while a caller is blocked, the counter wraps around, and semop(2) may falsely conclude that the original set still exists. The subsequent access to a semaphore within the set may then be out of bounds.

An unprivileged local user can trigger an out-of-bounds access on kernel heap memory, potentially leading to privilege escalation.

Scores and how they were measured

CVSS base severity

8.4

Version 3.1As of

CVSS:3.1/AV:L/AC:L/PR:N/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

0.1%

Scored Percentile 1.5%

Model and measurement source (opens a new tab)

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-2026-58098 (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

    Vendor advisory (via NVD references) (opens a new tab)

    The vendor advisory referenced by the CVE record, for affected versions and fixes.

    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

  4. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-58098, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

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

APA

KEVWire. (2026, October 19). When semop(2) blocks waiting for a semaphore condition, it releases the per-set lock and sleeps. (CVE-2026-58098). https://kevwire.com/record/CVE-2026-58098

MLA

"When semop(2) blocks waiting for a semaphore condition, it releases the per-set lock and sleeps. (CVE-2026-58098)." KEVWire, 19 Oct. 2026, kevwire.com/record/CVE-2026-58098.

Chicago

KEVWire. "When semop(2) blocks waiting for a semaphore condition, it releases the per-set lock and sleeps. (CVE-2026-58098)." Last modified October 19, 2026. https://kevwire.com/record/CVE-2026-58098.

Evidence summary (plain text)

When semop(2) blocks waiting for a semaphore condition, it releases the per-set lock and sleeps. (Oct 15, 2026).
When semop(2) blocks waiting for a semaphore condition, it releases the per-set lock and sleeps.  Upon waking, it checks the sequence number embedded in the semaphore set's IPC identifier to detect whether the set was removed while the caller was asleep.  This sequence number is only 15 bits wide.  If enough semaphore sets are created and destroyed in the same table slot while a caller is blocked, the counter wraps around, and semop(2) may falsely conclude that the original set still exists.  The subsequent access to a semaphore within the set may then be out of bounds.

An unprivileged local user can trigger an out-of-bounds access on kernel heap memory, potentially leading to privilege escalation.
CVSS 8.4 (version 3.1; evidence as of Oct 19, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-58098).
EPSS 0.1% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-58098&date=2026-10-26).
Sources:
NVD CVE-2026-58098: https://nvd.nist.gov/vuln/detail/CVE-2026-58098
Vendor advisory (via NVD references): https://security.freebsd.org/advisories/FreeBSD-SA-26:64.sysvsem.asc
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=3500
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-58098&date=2026-10-26
Record ID: CVE-2026-58098.
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: Oct 26, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

NVD status: Analyzed. 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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Record details

Record detail