---
id: "CVE-2026-99070"
kind: "vulnerability"
aliases: ["CVE-2026-99070"]
title: "Linux kernel: IPv6 route notification warning fires on benign size race"
severity: "unknown"
cvss: null
epss: 0.00209
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "ipv6", "linux-kernel", "routing"]
not_affected_if: ["default-config"]
published_at: "2026-10-23T13:17:30+00:00"
first_seen_at: "2026-10-23T21:57:34+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99070", "first_seen_at": "2026-10-23T21:57:34+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-99070", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Linux kernel: IPv6 route notification warning fires on benign size race

The Linux kernel's IPv6 code printed a warning when a route notification skb was too small, which can happen legitimately when a nexthop group changes concurrently. The fix removes the warning; the existing error path already frees the buffer and reports the error.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-10-23T21:57:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99070
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-99070

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

ipv6: do not warn on route notification size race

fib6_info_hw_flags_set() sizes the skb with rt6_nlmsg_size() and later
fills it with rt6_fill_node().  With nexthop compatibility mode enabled,
a concurrent replacement can grow the group between these independent
snapshots.  rt6_fill_node() 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.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_