Vulnerability-Lookup

CVE-2026-58083 (GCVE-0-2026-58083)

Vulnerability from cvelistv5 – Published: 2026-08-19 07:28 – Updated: 2026-08-19 11:57

Title

Use-after-free in kqueue copy-on-fork

Summary

While the kernel was copying knotes during fork, a knote with a timer-based filter could fire and be enqueued on the kqueue's active list before the copy was complete. The copy routine did not account for this and could enqueue the new knote a second time, corrupting the active list. In addition, the copy routine did not hold the appropriate locks while reading knote state, allowing further races. An unprivileged local user can trigger a use-after-free in the kernel, potentially leading to privilege escalation.

Severity

8.4 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-19 11:56 UTC

CWE

CWE-416 - Use After Free

Assigner

freebsd mitre root

References

1 reference

URL	Tags
https://security.freebsd.org/advisories/FreeBSD-S…	vendor-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
FreeBSD	FreeBSD	Affected: 15.1-RELEASE , < p2 (release)	guessed

Date Public

2026-07-29 22:40

Credits

Hazley Samsudin of GovTech CSG

Show details on NVD website

JSON

To clipboard

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  "containers": {
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        }
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          "descriptions": [
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          "tags": [
            "vendor-advisory"
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          "url": "https://security.freebsd.org/advisories/FreeBSD-SA-26:50.kqueue.asc"
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      "title": "Use-after-free in kqueue copy-on-fork",
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FKIE_CVE-2026-58083

Vulnerability from fkie_nvd - Published: 2026-08-19 08:17 - Updated: 2026-08-19 12:18

Severity

8.4 (High) - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	secteam@freebsd.org	https://security.freebsd.org/advisories/FreeBSD-SA-26:50.kqueue.asc

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unknown",
          "modules": [
            "kqueue"
          ],
          "product": "FreeBSD",
          "vendor": "FreeBSD",
          "versions": [
            {
              "lessThan": "p2",
              "status": "affected",
              "version": "15.1-RELEASE",
              "versionType": "release"
            }
          ]
        }
      ],
      "source": "secteam@freebsd.org"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "While the kernel was copying knotes during fork, a knote with a timer-based filter could fire and be enqueued on the kqueue\u0027s active list before the copy was complete.  The copy routine did not account for this and could enqueue the new knote a second time, corrupting the active list.  In addition, the copy routine did not hold the appropriate locks while reading knote state, allowing further races.\n\nAn unprivileged local user can trigger a use-after-free in the kernel, potentially leading to privilege escalation."
    }
  ],
  "id": "CVE-2026-58083",
  "lastModified": "2026-08-19T12:18:33.190",
  "metrics": {
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          "attackVector": "LOCAL",
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        "impactScore": 5.9,
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        "type": "Secondary"
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}

GHSA-J94H-9P69-VHVM

Vulnerability from github – Published: 2026-08-19 09:31 – Updated: 2026-08-19 12:32

Details

An unprivileged local user can trigger a use-after-free in the kernel, potentially leading to privilege escalation.

Severity

8.4 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-58083"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-19T08:17:12Z",
    "severity": "HIGH"
  },
  "details": "While the kernel was copying knotes during fork, a knote with a timer-based filter could fire and be enqueued on the kqueue\u0027s active list before the copy was complete.  The copy routine did not account for this and could enqueue the new knote a second time, corrupting the active list.  In addition, the copy routine did not hold the appropriate locks while reading knote state, allowing further races.\n\nAn unprivileged local user can trigger a use-after-free in the kernel, potentially leading to privilege escalation.",
  "id": "GHSA-j94h-9p69-vhvm",
  "modified": "2026-08-19T12:32:22Z",
  "published": "2026-08-19T09:31:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-58083"
    },
    {
      "type": "WEB",
      "url": "https://security.freebsd.org/advisories/FreeBSD-SA-26:50.kqueue.asc"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-58083 (GCVE-0-2026-58083)

FKIE_CVE-2026-58083

GHSA-J94H-9P69-VHVM

Tags

Sightings

Nomenclature