CVE-2026-99070

Kernel warnings via IPv6 route-notification race

Published Oct 23, 2026 · Updated Oct 23, 2026

A race in Linux IPv6 route notifications allows attackers to trigger spurious kernel warnings during concurrent nexthop replacement. fib6_info_hw_flags_set() sizes and fills its buffer from separate snapshots, then treats legitimate -EMSGSIZE from rt6_fill_node() as a bug. Nexthop compatibility mode must be enabled; notification failure is handled, but panic_on_warn=1 turns the warning into a kernel crash.

CVSS severityUnavailable
Unscored
EPSS probability0.17%
Next 30 days · Nov 1, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A race in Linux IPv6 route notifications allows attackers to trigger spurious kernel warnings during concurrent nexthop replacement. fib6_info_hw_flags_set() sizes and fills its buffer from separate snapshots, then treats legitimate -EMSGSIZE from rt6_fill_node() as a bug. Nexthop compatibility mode must be enabled; notification failure is handled, but panic_on_warn=1 turns the warning into a kernel crash.

The record

CVE
CVE-2026-99070
Published
Oct 23, 2026
Updated
Oct 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
Unavailable
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=907eea486888cfe118c19759bbc4b8fca2e004df <291fe0bafee78c95f9f2e7f579f17793fd5a1e5a
  3. Affected versionversion=907eea486888cfe118c19759bbc4b8fca2e004df <4ac7d92a4698e34e614c254359665b9de1f65283
  4. Affected versionversion=907eea486888cfe118c19759bbc4b8fca2e004df <7b112bd43f1172fb152e848570a957467008a5ae
  5. Affected versionversion=907eea486888cfe118c19759bbc4b8fca2e004df <8a3b935b6b6037eefb36bd27a60793a008358e8d
  6. Affected versionversion=907eea486888cfe118c19759bbc4b8fca2e004df <c97426ec649d99596d8969e1a052c16b14b7b485

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=907eea486888cfe118c19759bbc4b8fca2e004df <291fe0bafee78c95f9f2e7f579f17793fd5a1e5a; version=907eea486888cfe118c19759bbc4b8fca2e004df <4ac7d92a4698e34e614c254359665b9de1f65283; version=907eea486888cfe118c19759bbc4b8fca2e004df <7b112bd43f1172fb152e848570a957467008a5ae; version=907eea486888cfe118c19759bbc4b8fca2e004df <8a3b935b6b6037eefb36bd27a60793a008358e8d; version=907eea486888cfe118c19759bbc4b8fca2e004df <c97426ec649d99596d8969e1a052c16b14b7b485

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.

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

No observations available

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

Weakness, pattern, technique

No sourced classifications are available.

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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