# CVE-2026-98603: ovpn: replace bind when clearing stale local source

> A race condition in the Linux kernel OVPN module allows concurrent access to torn IPv6 addresses, potentially causing crashes or information leaks.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98603, DEBIAN-CVE-2026-98603, GHSA-fvvm-56rx-vqjg, UBUNTU-CVE-2026-98603

## What is CVE-2026-98603?

CVE-2026-98603 is a vulnerability in Linux, published on 18 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

## Which versions are affected by CVE-2026-98603?


## How do I fix CVE-2026-98603?

Apply the vendor's patch.

## Is CVE-2026-98603 being exploited?

There is no known exploitation of CVE-2026-98603 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98603 and fix it if it is affected.

What it is: CVE-2026-98603 is a vulnerability in Linux, published on 18 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98603 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98603/ (Markdown: https://insights.sbomify.com/CVE-2026-98603/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98603
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98603
- OSV: https://osv.dev/vulnerability/CVE-2026-98603

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98603/
Summaries are generated and may contain mistakes; the official description above is the record.