# CVE-2026-80788: nvmet-tcp: Do not WARN on remotely-controlled oversized SGL allocations

> A remote attacker can trigger a kernel warning via oversized SGL allocations in nvmet-tcp, potentially causing a denial of service if panic-on-warn is enabled.

- **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-99503, BELL-CVE-2026-80788, DEBIAN-CVE-2026-80788, GHSA-wcww-94r3-9q6w, UBUNTU-CVE-2026-80788

## What is CVE-2026-80788?

CVE-2026-80788 is a denial of service 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:

nvmet-tcp: Do not WARN on remotely-controlled oversized SGL allocations

When fuzzing the nvme target code, I tripped a kernel warning in
nvmet_tcp_map_data() because the length passed into the allocator is
controlled by the remote initiator.

A remote initiator that sends a command with an SGL claiming a huge
number, can create a scatterlist and iovec allocation of over 1 million
entries, which causes the backing kmalloc call to exceed MAX_PAGE_ORDER
and then the page allocator will trip on a WARN_ON_ONCE_GFP() message:

  WARNING: mm/page_alloc.c:5280 __alloc_frozen_pages_noprof
  Workqueue: nvmet_tcp_wq nvmet_tcp_io_work
  ...
  sgl_alloc_order
  nvmet_tcp_map_data
  nvmet_tcp_try_recv_pdu

As it's never good to trip a kernel warning remotely due to many systems
having panic-on-warn enabled, let's silence it by just add GFP_NOWARN to
the allocation flags.

## Which versions are affected by CVE-2026-80788?


## How do I fix CVE-2026-80788?

Apply the vendor's patch.

## Is CVE-2026-80788 being exploited?

There is no known exploitation of CVE-2026-80788 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80788 and fix it if it is affected.

What it is: CVE-2026-80788 is a denial of service 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-2026-80788 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-2026-80788/ (Markdown: https://insights.sbomify.com/CVE-2026-80788/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80788
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80788
- OSV: https://osv.dev/vulnerability/CVE-2026-80788

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80788/
Summaries are generated and may contain mistakes; the official description above is the record.