# CVE-2026-98449: smb: client: delete compound mids on send failure before unlock

> A double credit release in the Linux kernel SMB client can cause a kernel warning and potential denial of service when a compound request send fails.

- **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:** AZL-109380, BELL-CVE-2026-98449, DEBIAN-CVE-2026-98449, GHSA-2758-q84j-4rxj, UBUNTU-CVE-2026-98449

## What is CVE-2026-98449?

CVE-2026-98449 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:

smb: client: delete compound mids on send failure before unlock

When sending a compound request fails, smb_send_rqst() kicks off a
reconnect. compound_send_recv() still has those mids on pending_mid_q,
but it unlocks the server without removing them first.

During reconnect, cifs_abort_connection() walks pending_mid_q and runs
each mid callback. With no response yet, those callbacks return credits
and drop in_flight. Then compound_send_recv()'s send-error path returns
the same credits again. in_flight ends up decremented twice and
smb2_add_credits() WARNs.

syzbot hits this during SMB2_negotiate when the socket send fails.

cifs_call_async() already calls delete_mid() before unlock on send
failure. Do the same for compound chains and set cancelled_mid[] so the
out: path does not delete them again.

## Which versions are affected by CVE-2026-98449?


## How do I fix CVE-2026-98449?

Apply the vendor's patch.

## Is CVE-2026-98449 being exploited?

There is no known exploitation of CVE-2026-98449 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98449 and fix it if it is affected.

What it is: CVE-2026-98449 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-2026-98449 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-2026-98449/ (Markdown: https://insights.sbomify.com/CVE-2026-98449/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98449
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98449
- OSV: https://osv.dev/vulnerability/CVE-2026-98449

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98449/
Summaries are generated and may contain mistakes; the official description above is the record.