CVE-2025-39874

Network-device hang via recursive lower-device locking

Published Sep 23, 2025 · Updated Sep 23, 2025

Denial of service in Linux kernel 6.15 allows local users to hang network-device updates through an ETHTOOL_SFEATURES request. In drivers/net/macsec.c, macsec_notify handles a feature-change notification by resynchronizing an unsynchronized lower device and recursively acquiring its existing lock. Low-privilege local access and a macsec link over the targeted lower interface are required; the network-device update remains stuck.

CVSS severity5.5
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux kernel 6.15 allows local users to hang network-device updates through an ETHTOOL_SFEATURES request. In drivers/net/macsec.c, macsec_notify handles a feature-change notification by resynchronizing an unsynchronized lower device and recursively acquiring its existing lock. Low-privilege local access and a macsec link over the targeted lower interface are required; the network-device update remains stuck.

The record

CVE
CVE-2025-39874
Published
Sep 23, 2025
Updated
Sep 23, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 23, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=6.15
  2. Affected versionversion=7e4d784f5810bba76c4593791028e13cce4af547 <0f82c3ba66c6b2e3cde0f255156a753b108ee9dc
  3. Affected versionversion=7e4d784f5810bba76c4593791028e13cce4af547 <d7624629ccf47135c65fef0701fa0d9a115b87f3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.15; version=7e4d784f5810bba76c4593791028e13cce4af547 <0f82c3ba66c6b2e3cde0f255156a753b108ee9dc; version=7e4d784f5810bba76c4593791028e13cce4af547 <d7624629ccf47135c65fef0701fa0d9a115b87f3

Published CVSS scores

5.5CISA ADPCVSS: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.

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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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