CVE-2026-99072

Kernel crash via nexthop-group shrink race

Published Oct 23, 2026 · Updated Oct 23, 2026

Linux 5.12 has a race in IPv4 route notification sizing that allows local users to trigger a kernel crash via nexthop replacement. In fib_nlmsg_size(), separate reads of the nexthop group let a concurrent RTM_NEWNEXTHOP shrink invalidate a path index, passing NULL to fib_nexthop_nlmsg_size(). Triggering the race requires nexthop replacement during asynchronous hardware-flag notification sizing and network-administration privileges; code execution is not established.

CVSS severityUnavailable
Unscored
EPSS probability0.16%
Next 30 days · Nov 1, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Linux 5.12 has a race in IPv4 route notification sizing that allows local users to trigger a kernel crash via nexthop replacement. In fib_nlmsg_size(), separate reads of the nexthop group let a concurrent RTM_NEWNEXTHOP shrink invalidate a path index, passing NULL to fib_nexthop_nlmsg_size(). Triggering the race requires nexthop replacement during asynchronous hardware-flag notification sizing and network-administration privileges; code execution is not established.

The record

CVE
CVE-2026-99072
Published
Oct 23, 2026
Updated
Oct 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 23, 2026Record 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=5.12
  2. Affected versionversion=680aea08e78c003292415518ad270bc20f9c80b1 <72d9d17092bb37b0717f12042a0817d01a1f9e78
  3. Affected versionversion=680aea08e78c003292415518ad270bc20f9c80b1 <ad1c9f1b98c92609e9bb2ae8f05916defc3b0a54
  4. Affected versionversion=680aea08e78c003292415518ad270bc20f9c80b1 <ad2b3a68b8a7d5d27de88e05674e4adb1ce46d88
  5. Affected versionversion=680aea08e78c003292415518ad270bc20f9c80b1 <c1f48d1c2d5e9efd904dbbc2f2b3d41543e55c49
  6. Affected versionversion=680aea08e78c003292415518ad270bc20f9c80b1 <d3daa33c7af92e38f2274bbd2576f58bfbaf89e6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=680aea08e78c003292415518ad270bc20f9c80b1 <72d9d17092bb37b0717f12042a0817d01a1f9e78; version=680aea08e78c003292415518ad270bc20f9c80b1 <ad1c9f1b98c92609e9bb2ae8f05916defc3b0a54; version=680aea08e78c003292415518ad270bc20f9c80b1 <ad2b3a68b8a7d5d27de88e05674e4adb1ce46d88; version=680aea08e78c003292415518ad270bc20f9c80b1 <c1f48d1c2d5e9efd904dbbc2f2b3d41543e55c49; version=680aea08e78c003292415518ad270bc20f9c80b1 <d3daa33c7af92e38f2274bbd2576f58bfbaf89e6

Published CVSS scores

No CVSS assessment is available in this record.

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.

Activity data is delayed. The latest report is Sep 28, 2026.

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No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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