# CVE-2026-80792: ipv6: fix use-after-free in ip6_finish_output2()

> A use-after-free in the Linux kernel IPv6 stack allows attackers to leak sensitive data, corrupt neighbor tables, or crash the system via crafted network traffic.

- **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:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-99428, BELL-CVE-2026-80792, DEBIAN-CVE-2026-80792, GHSA-4jhv-hqg8-9j35, UBUNTU-CVE-2026-80792

## What is CVE-2026-80792?

CVE-2026-80792 is an use after free vulnerability in Linux, published on 4 Sep 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:

ipv6: fix use-after-free in ip6_finish_output2()

ip6_finish_output2() caches a pointer to the IPv6 destination
address (daddr) before invoking lwtunnel_xmit().  The LWT-BPF
transmit path or other encapsulation operations within
lwtunnel_xmit() can reallocate the skb head, freeing the memory
that daddr points to.  When lwtunnel_xmit() returns
LWTUNNEL_XMIT_CONTINUE, the function continues to use the stale
daddr pointer to compute the nexthop and to look up or create the
neighbour entry.  This results in a use-after-free read, which can
leak sensitive kernel data, pollute the neighbour table with
arbitrary values, misdirect traffic, or crash the system.

Fix this by re-fetching the IPv6 header and the destination
address pointer after lwtunnel_xmit() returns
LWTUNNEL_XMIT_CONTINUE, ensuring that the subsequent nexthop
computation and neighbour lookup operate on valid memory.

## Which versions are affected by CVE-2026-80792?


## How do I fix CVE-2026-80792?

Apply the vendor's patch.

## Is CVE-2026-80792 being exploited?

There is no known exploitation of CVE-2026-80792 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80792 and fix it if it is affected.

What it is: CVE-2026-80792 is an use after free vulnerability in Linux, published on 4 Sep 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-2026-80792 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-2026-80792/ (Markdown: https://insights.sbomify.com/CVE-2026-80792/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80792
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80792
- OSV: https://osv.dev/vulnerability/CVE-2026-80792

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80792/
Summaries are generated and may contain mistakes; the official description above is the record.