# CVE-2026-98277: eth: fbnic: ring the doorbell if a burst ends in a drop

> A missing doorbell ring in the fbnic driver can cause network transmission stalls and denial of service when packet bursts end in drops.

- **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:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98277, DEBIAN-CVE-2026-98277, GHSA-xjm7-64jw-75jr, UBUNTU-CVE-2026-98277

## What is CVE-2026-98277?

CVE-2026-98277 is a denial of service vulnerability in Linux, published on 6 Oct 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:

eth: fbnic: ring the doorbell if a burst ends in a drop

fbnic_tx_map() skips the doorbell write, and the completion request,
for every packet handed to it with xmit_more set, counting on the
packet which ends the burst to publish them all. When that packet is
dropped instead - skb_put_padto(), skb_cow_head() or a DMA mapping
failure - nothing rings. The descriptors of the preceding packets stay
invisible to the HW until the next transmit on that queue, which for a
burst-then-idle workload may never come.

Remember the meta descriptor of the last packet left without a doorbell
and flush it from the error paths. The completion request has to be set
on that descriptor rather than simply writing the tail, otherwise the HW
would transmit the packets but never report a head, and the ring would
fill up and stall for good.

This is very similar to Joe's recent series of fixes for bnxt.
Not seen in real life, reproduced under QEMU with failure injection.

## Which versions are affected by CVE-2026-98277?


## How do I fix CVE-2026-98277?

Apply the vendor's patch.

## Is CVE-2026-98277 being exploited?

There is no known exploitation of CVE-2026-98277 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98277 and fix it if it is affected.

What it is: CVE-2026-98277 is a denial of service vulnerability in Linux, published on 6 Oct 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-2026-98277 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-2026-98277/ (Markdown: https://insights.sbomify.com/CVE-2026-98277/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98277
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98277
- OSV: https://osv.dev/vulnerability/CVE-2026-98277

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98277/
Summaries are generated and may contain mistakes; the official description above is the record.