VulnerabilityPublished 23 Oct 2026

CVE-2026-99072: Linux kernel · ipv4: stop route notification sizing when nexthop group shrinks

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in d3daa33c7af92e38f2274bbd2576f58bfbaf89e6 : 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: 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in d3daa33c7af92e38f2274bbd2576f58bfbaf89e6, c1f48d1c2d5e9efd904dbbc2f2b3d41543e55c49, ad2b3a68b8a7d5d27de88e05674e4adb1ce46d88 +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, < d3daa33c7af92e38f2274bbd2576f58bfbaf89e6	Fixed in d3daa33c7af92e38f2274bbd2576f58bfbaf89e6
LinuxLinux	Affected ≥ 680aea08e78c003292415518ad270bc20f9c80b1, < c1f48d1c2d5e9efd904dbbc2f2b3d41543e55c49	Fixed in c1f48d1c2d5e9efd904dbbc2f2b3d41543e55c49
LinuxLinux	Affected ≥ 680aea08e78c003292415518ad270bc20f9c80b1, < ad2b3a68b8a7d5d27de88e05674e4adb1ce46d88	Fixed in ad2b3a68b8a7d5d27de88e05674e4adb1ce46d88
LinuxLinux	Affected ≥ 680aea08e78c003292415518ad270bc20f9c80b1, < ad1c9f1b98c92609e9bb2ae8f05916defc3b0a54	Fixed in ad1c9f1b98c92609e9bb2ae8f05916defc3b0a54
LinuxLinux	Affected ≥ 680aea08e78c003292415518ad270bc20f9c80b1, < 72d9d17092bb37b0717f12042a0817d01a1f9e78	Fixed in 72d9d17092bb37b0717f12042a0817d01a1f9e78
LinuxLinux	Affected =5.12	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: ipv4: stop route notification sizing when nexthop group shrinks Commit 680aea08e78c ("net: ipv4: Emit notification when fib hardware flags are changed") added an RCU-only fib_nlmsg_size() call for asynchronous hardware flag notifications. fib_nlmsg_size() checks fib_info_num_path() before each iteration, then fib_info_nhc() independently reloads nh->nh_grp. If RTM_NEWNEXTHOP replaces a group with fewer paths between those loads, fib_info_nhc() returns NULL and fib_nexthop_nlmsg_size() dereferences it. Stop sizing when the indexed path is absent. Nexthop groups are dense, so the current snapshot has no later path.

References

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