# CVE-2026-89776: vxlan: vnifilter: enforce exact length of GROUP/GROUP6 attributes

> A local attacker can trigger a kernel memory over-read in VXLAN VNI filters, disclosing uninitialized kernel memory via netlink responses.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-101391, BELL-CVE-2026-89776, DEBIAN-CVE-2026-89776, GHSA-vf8c-65h3-589v, UBUNTU-CVE-2026-89776

## What is CVE-2026-89776?

CVE-2026-89776 is a vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

vxlan: vnifilter: enforce exact length of GROUP/GROUP6 attributes

The VXLAN VNI filter entry policy declares the GROUP/GROUP6 address
attributes as NLA_BINARY with only a maximum length, so validate_nla()
accepts a payload shorter than the address. The GROUP consumer reads it
with nla_get_in_addr(), an unconditional 4-byte load, so a short
attribute over-reads up to 3 bytes of uninitialised slab data, which are
stored into remote_ip and echoed back via RTM_GETTUNNEL, disclosing
kernel memory.

Switch both entries to NLA_POLICY_EXACT_LEN() so the validator rejects
any GROUP/GROUP6 that is not exactly 4 / 16 bytes; a valid address is
always sent at full width.

## Which versions are affected by CVE-2026-89776?


## How do I fix CVE-2026-89776?

Apply the vendor's patch.

## Is CVE-2026-89776 being exploited?

There is no known exploitation of CVE-2026-89776 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89776 and fix it if it is affected.

What it is: CVE-2026-89776 is a vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-89776 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-2026-89776/ (Markdown: https://insights.sbomify.com/CVE-2026-89776/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89776
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89776
- OSV: https://osv.dev/vulnerability/CVE-2026-89776

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89776/
Summaries are generated and may contain mistakes; the official description above is the record.