# CVE-2026-93785: cifs: validate idmap key payload length

> An attacker with local access can trigger an integer overflow in the CIFS idmap key handling, leading to inconsistent payload bounds and potential memory safety issues.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 3 Oct 2026
- **Also known as:** AZL-103994, BELL-CVE-2026-93785, DEBIAN-CVE-2026-93785, GHSA-qvvf-f4g9-5p95, UBUNTU-CVE-2026-93785

## What is CVE-2026-93785?

CVE-2026-93785 is a vulnerability in Linux, published on 24 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:

cifs: validate idmap key payload length

The cifs.idmap key type stores its payload length in key->datalen, which
is limited to U16_MAX.  Accepting a larger key payload truncates the
recorded length and can make later users interpret the payload using
inconsistent bounds.

Reject oversized preparsed payloads before allocating or copying them.
This keeps key->datalen consistent with the stored data for both inline
and separately allocated idmap payloads.

## Which versions are affected by CVE-2026-93785?


## How do I fix CVE-2026-93785?

Apply the vendor's patch.

## Is CVE-2026-93785 being exploited?

There is no known exploitation of CVE-2026-93785 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93785 and fix it if it is affected.

What it is: CVE-2026-93785 is a vulnerability in Linux, published on 24 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-2026-93785 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-2026-93785/ (Markdown: https://insights.sbomify.com/CVE-2026-93785/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93785
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93785
- OSV: https://osv.dev/vulnerability/CVE-2026-93785

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93785/
Summaries are generated and may contain mistakes; the official description above is the record.