# CVE-2026-98615: eth: fbnic: Set AW_FLUSH_MODE alongside AW_FLUSH when flushing the mailbox

> A flaw in the fbnic network driver causes a denial of service during mailbox teardown due to incomplete flush operations, requiring a kernel patch.

- **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:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98615, DEBIAN-CVE-2026-98615, GHSA-83c5-m4vx-chr4, UBUNTU-CVE-2026-98615

## What is CVE-2026-98615?

CVE-2026-98615 is a denial of service vulnerability in Linux, published on 18 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: Set AW_FLUSH_MODE alongside AW_FLUSH when flushing the mailbox

When tearing down the FW mailbox Rx ring, fbnic_mbx_reset_desc_ring()
writes AW_CFG with FLUSH set and everything else, BME included, cleared.
Clearing BME halts the device's writes to the host but leaves the staged
requests parked in the PUL write pipeline rather than draining them, so
on the write path FLUSH alone never terminates the outstanding requests
and the flush the firmware waits on never completes.

Add the FLUSH_MODE definition and set both bits so the staged writes
drain out of the pipeline on their own. BME stays cleared, so nothing
lands on the host; it is restored later in fbnic_mbx_init_desc_ring()
when the ring is rebuilt, once the outstanding writes are gone.

The read path is unaffected. AR_CFG has no equivalent mode bit and
AR_FLUSH terminates the outstanding reads by itself, so it is left as
is.

Both writes remain plain stores rather than read-modify-writes. That is
deliberate: the matching write in fbnic_mbx_init_desc_ring() restores
BME and the TLP attributes, and clears both flush bits as a side effect.

## Which versions are affected by CVE-2026-98615?


## How do I fix CVE-2026-98615?

Apply the vendor's patch.

## Is CVE-2026-98615 being exploited?

There is no known exploitation of CVE-2026-98615 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98615 and fix it if it is affected.

What it is: CVE-2026-98615 is a denial of service vulnerability in Linux, published on 18 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-2026-98615 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-2026-98615/ (Markdown: https://insights.sbomify.com/CVE-2026-98615/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98615
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98615
- OSV: https://osv.dev/vulnerability/CVE-2026-98615

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98615/
Summaries are generated and may contain mistakes; the official description above is the record.