# CVE-2026-89565: ipip: fix skb leak in collect_md mode when metadata_dst allocation fails

> A memory leak in the Linux kernel's IPIP tunnel driver can cause denial of service when metadata allocation fails in collect_md mode.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100745, BELL-CVE-2026-89565, DEBIAN-CVE-2026-89565, GHSA-x2xj-xv7g-fj5c, UBUNTU-CVE-2026-89565

## What is CVE-2026-89565?

CVE-2026-89565 is a memory corruption vulnerability in Linux, published on 11 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:

ipip: fix skb leak in collect_md mode when metadata_dst allocation fails

In collect_md mode ipip_tunnel_rcv() returns 0 without freeing the skb
when ip_tun_rx_dst() fails to allocate the metadata_dst. ipip_rcv() and
mplsip_rcv() are registered as xfrm_tunnel handlers, so tunnel4_rcv()
and tunnelmpls4_rcv() read the zero return as "the packet has been
consumed" and do not free it either. The skb is leaked.

The other tunnel drivers all dispose of the packet at this point:
ip6_tunnel.c jumps to its drop label, ip_gre.c and ip6_gre.c return
PACKET_REJECT, which makes gre_rcv() free the skb. Only ipip returns 0.

Jump to the existing drop label instead. It frees the skb and still
returns 0, so the packet keeps being reported as consumed, which is what
we want here: the outer header has already been pulled, and neither the
remaining handlers nor an ICMP unreachable have any use for it.

Triggering this needs an ipip or mplsip tunnel in collect_md mode and an
atomic allocation failure, which is why it has gone unnoticed.

## Which versions are affected by CVE-2026-89565?


## How do I fix CVE-2026-89565?

Apply the vendor's patch.

## Is CVE-2026-89565 being exploited?

There is no known exploitation of CVE-2026-89565 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89565 and fix it if it is affected.

What it is: CVE-2026-89565 is a memory corruption vulnerability in Linux, published on 11 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-2026-89565 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-2026-89565/ (Markdown: https://insights.sbomify.com/CVE-2026-89565/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89565
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89565
- OSV: https://osv.dev/vulnerability/CVE-2026-89565

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89565/
Summaries are generated and may contain mistakes; the official description above is the record.