CVE-2025-39926

Denial of service via unauthorized genetlink callbacks

Published Oct 1, 2025 · Updated May 11, 2026

Improper permission checks in the Linux kernel allow local users to cause a service interrupt through an unauthorized genetlink bind. genl_bind() called each family's bind callback even after capability checks set -EPERM, so unauthorized callers could make callbacks run despite a failed syscall. Low-privileged local access is required; published scoring limits the consequence to availability loss.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper permission checks in the Linux kernel allow local users to cause a service interrupt through an unauthorized genetlink bind. genl_bind() called each family's bind callback even after capability checks set -EPERM, so unauthorized callers could make callbacks run despite a failed syscall. Low-privileged local access is required; published scoring limits the consequence to availability loss.

The record

CVE
CVE-2025-39926
Published
Oct 1, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 1, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3de21a8990d3c2cc507e9cc4ed00f36358d5b93e <1dbfb0363224f6da56f6655d596dc5097308d6f5
  2. Affected versionversion=3de21a8990d3c2cc507e9cc4ed00f36358d5b93e <8858c1e9405906c09589d7c336f04058ea198207
  3. Affected versionversion=3de21a8990d3c2cc507e9cc4ed00f36358d5b93e <98c9d884047a3051c203708914a874dece3cbe54
  4. Affected versionversion=6.9

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3de21a8990d3c2cc507e9cc4ed00f36358d5b93e <1dbfb0363224f6da56f6655d596dc5097308d6f5; version=3de21a8990d3c2cc507e9cc4ed00f36358d5b93e <8858c1e9405906c09589d7c336f04058ea198207; version=3de21a8990d3c2cc507e9cc4ed00f36358d5b93e <98c9d884047a3051c203708914a874dece3cbe54; version=6.9

Published CVSS scores

5.5OracleCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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