CVE-2025-39673

Kernel panic via PPP channel teardown races

Published Sep 5, 2025 · Updated Sep 5, 2025

Race conditions in the PPP subsystem in affected Linux kernels allow local users to trigger a kernel panic during channel teardown. ppp_fill_forward_path reads the changing ppp->channels list without the required lock and dereferences pch->chan after ppp_unregister_channel can set it to NULL. Exploitation requires low-privileged local access and a concurrent PPP channel disconnect or unregister operation; the bounded impact is a host crash.

CVSS severity9.8
Critical
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race conditions in the PPP subsystem in affected Linux kernels allow local users to trigger a kernel panic during channel teardown. ppp_fill_forward_path reads the changing ppp->channels list without the required lock and dereferences pch->chan after ppp_unregister_channel can set it to NULL. Exploitation requires low-privileged local access and a concurrent PPP channel disconnect or unregister operation; the bounded impact is a host crash.

The record

CVE
CVE-2025-39673
Published
Sep 5, 2025
Updated
Sep 5, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-362, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 5, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 5, 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=5.13
  2. Affected versionversion=f6efc675c9dd8d93f826b79ae7e33e03301db609 <0417adf367a0af11adf7ace849af4638cfb573f7
  3. Affected versionversion=f6efc675c9dd8d93f826b79ae7e33e03301db609 <0f1630be6fcca3f0c63e4b242ad202e5cde28a40
  4. Affected versionversion=f6efc675c9dd8d93f826b79ae7e33e03301db609 <94731cc551e29511d85aa8dec61a6c071b1f2430
  5. Affected versionversion=f6efc675c9dd8d93f826b79ae7e33e03301db609 <9a1969fbffc1f1900d92d7594b1b7d8d72ef3dc7
  6. Affected versionversion=f6efc675c9dd8d93f826b79ae7e33e03301db609 <ca18d751bcc9faf5b7e82e9fae1223d103928181
  7. Affected versionversion=f6efc675c9dd8d93f826b79ae7e33e03301db609 <f97f6475fdcb3c28ff3c55cc4b7bde632119ec08

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.13; version=f6efc675c9dd8d93f826b79ae7e33e03301db609 <0417adf367a0af11adf7ace849af4638cfb573f7; version=f6efc675c9dd8d93f826b79ae7e33e03301db609 <0f1630be6fcca3f0c63e4b242ad202e5cde28a40; version=f6efc675c9dd8d93f826b79ae7e33e03301db609 <94731cc551e29511d85aa8dec61a6c071b1f2430; version=f6efc675c9dd8d93f826b79ae7e33e03301db609 <9a1969fbffc1f1900d92d7594b1b7d8d72ef3dc7; version=f6efc675c9dd8d93f826b79ae7e33e03301db609 <ca18d751bcc9faf5b7e82e9fae1223d103928181; version=f6efc675c9dd8d93f826b79ae7e33e03301db609 <f97f6475fdcb3c28ff3c55cc4b7bde632119ec08

Published CVSS scores

5.9Oracle LinuxCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
9.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
4.7NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5SUSECVSS: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

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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