VulnerabilityPublished 23 Oct 2026

CVE-2026-99071: Linux kernel · ipv4: do not warn on route notification size race

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in e02a5b6588161673ef75a4bc5cdfb62bd493374d : update Linux kernel when convenient.

Data as of 26 Oct 2026, 13:07 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in e02a5b6588161673ef75a4bc5cdfb62bd493374d, 221ef5e1e44a044790f0f54e6aa237883f475a4d, 088ba80eef85fa7a5ad8f9e7c82b403c99242b56 +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 ≥ 680aea08e78c003292415518ad270bc20f9c80b1, < e02a5b6588161673ef75a4bc5cdfb62bd493374d	Fixed in e02a5b6588161673ef75a4bc5cdfb62bd493374d
LinuxLinux	Affected ≥ 680aea08e78c003292415518ad270bc20f9c80b1, < 221ef5e1e44a044790f0f54e6aa237883f475a4d	Fixed in 221ef5e1e44a044790f0f54e6aa237883f475a4d
LinuxLinux	Affected ≥ 680aea08e78c003292415518ad270bc20f9c80b1, < 088ba80eef85fa7a5ad8f9e7c82b403c99242b56	Fixed in 088ba80eef85fa7a5ad8f9e7c82b403c99242b56
LinuxLinux	Affected ≥ 680aea08e78c003292415518ad270bc20f9c80b1, < 78a1cf5c54b2f795c81fedb530755a8d01cc84f0	Fixed in 78a1cf5c54b2f795c81fedb530755a8d01cc84f0
LinuxLinux	Affected ≥ 680aea08e78c003292415518ad270bc20f9c80b1, < 7dfa7ca97f3ac46353edd4cc44f7733758e4535b	Fixed in 7dfa7ca97f3ac46353edd4cc44f7733758e4535b
LinuxLinux	Affected =5.12	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: ipv4: do not warn on route notification size race Commit 680aea08e78c ("net: ipv4: Emit notification when fib hardware flags are changed") added asynchronous route notifications for hardware flag changes. fib_alias_hw_flags_set() sizes the skb with fib_nlmsg_size() and later fills it with fib_dump_info() while holding only RCU. With nexthop compatibility mode enabled, a concurrent replacement can grow the group between these independent snapshots. fib_dump_info() can then legitimately return -EMSGSIZE, so the warning does not prove a sizing bug. Remove the warning. The existing error path still frees the skb and reports the error to listeners.

References

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