---
id: "CVE-2026-98603"
kind: "vulnerability"
aliases: ["CVE-2026-98603"]
title: "Linux kernel ovpn: unlocked source-address update can tear IPv6 reads"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "linux-kernel", "openvpn", "ovpn", "self-hosted"]
not_affected_if: ["ovpn-module-not-loaded"]
published_at: "2026-10-18T16:17:13+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:21:31+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98603", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel ovpn: unlocked source-address update can tear IPv6 reads

The Linux kernel's ovpn driver clears a peer's remembered local source address in place while concurrent transmit paths read it without a lock, so an IPv6 reader can see a torn address. The sources do not state a confirmed attacker outcome.

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

## How to check

- unknown

## Fix

- Update to a Linux kernel release that includes the upstream commit replacing the bind when clearing stale local source in ovpn.

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98603

## From the sources

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

ovpn: replace bind when clearing stale local source

The UDP output fallback clears bind->local in place when the remembered
source address is no longer usable. The bind is RCU-published and read
locklessly by concurrent TX, so an IPv6 reader can observe a torn
address.

Retry the route lookup with source address autoselection without
modifying the bind. After a successful lookup, revalidate the bind and
route key under peer->lock, reset the dst cache, and best-effort publish
a replacement bind with a wildcard local address.

Do not cache the resolved dst when clearing the local source. Replacing
the source invalidates all per-CPU cache entries, while
dst_cache_set_ip4 and dst_cache_set_ip6 update only the current CPU
slot. The current packet can still use the resolved route; if bind
allocation fails, a later cache miss retries the repair.

---

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