VulnerabilityPublished 23 Oct 2026

CVE-2026-99070: Linux kernel · ipv6: do not warn on route notification size race

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in c97426ec649d99596d8969e1a052c16b14b7b485 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 17:30 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in c97426ec649d99596d8969e1a052c16b14b7b485, 291fe0bafee78c95f9f2e7f579f17793fd5a1e5a, 8a3b935b6b6037eefb36bd27a60793a008358e8d +2

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 907eea486888cfe118c19759bbc4b8fca2e004df, < c97426ec649d99596d8969e1a052c16b14b7b485	Fixed in c97426ec649d99596d8969e1a052c16b14b7b485
LinuxLinux	Affected ≥ 907eea486888cfe118c19759bbc4b8fca2e004df, < 291fe0bafee78c95f9f2e7f579f17793fd5a1e5a	Fixed in 291fe0bafee78c95f9f2e7f579f17793fd5a1e5a
LinuxLinux	Affected ≥ 907eea486888cfe118c19759bbc4b8fca2e004df, < 8a3b935b6b6037eefb36bd27a60793a008358e8d	Fixed in 8a3b935b6b6037eefb36bd27a60793a008358e8d
LinuxLinux	Affected ≥ 907eea486888cfe118c19759bbc4b8fca2e004df, < 7b112bd43f1172fb152e848570a957467008a5ae	Fixed in 7b112bd43f1172fb152e848570a957467008a5ae
LinuxLinux	Affected ≥ 907eea486888cfe118c19759bbc4b8fca2e004df, < 4ac7d92a4698e34e614c254359665b9de1f65283	Fixed in 4ac7d92a4698e34e614c254359665b9de1f65283
LinuxLinux	Affected =5.12	Fixed in–

AI-suggested

A fix is available and has been applied in the Linux kernel commits identified by the fixedVersions hashes. Users should update to a kernel version including these commits to remove the misleading warning. No additional action is required as the error handling remains effective.

Description

This vulnerability in the Linux kernel relates to a warning triggered by a race condition in IPv6 route notification sizing. The issue occurs when the kernel's fib6_info_hw_flags_set() function sizes a socket buffer and later fills it, but concurrent changes can cause legitimate size errors that were previously warned as bugs. The fix removes the misleading warning while preserving the error handling path.

Impact

The vulnerability does not represent a functional bug or security flaw but rather a misleading warning about a race condition in route notification sizing. The error path remains intact, ensuring proper error reporting and resource cleanup. There is no indication of exploitation or adverse security impact.

Summary

CVE-2026-99070 addresses a Linux kernel IPv6 subsystem issue where fib6_info_hw_flags_set() sizes the skb using rt6_nlmsg_size() and later fills it with rt6_fill_node(). With nexthop compatibility mode enabled, concurrent replacements can cause the group size to grow between these snapshots, causing rt6_fill_node() to return -EMSGSIZE legitimately. Previously, this triggered a warning that incorrectly suggested a sizing bug. The patch removes this warning but retains the error handling that frees the skb and reports the error to listeners.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 15:31 UTC

Technical details

References

Community reviews

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