# CVE-2026-97990: vdpa_sim_net: check TX pull result before RX copy

> A missing check in the Linux kernel's vdpa_sim_net driver allows negative error codes to become large lengths, potentially causing memory corruption or crashes.

- **Severity:** High 7.5 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:H`)
- **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:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-104775, BELL-CVE-2026-97990, DEBIAN-CVE-2026-97990, GHSA-w85p-r6cx-8whc, UBUNTU-CVE-2026-97990

## What is CVE-2026-97990?

CVE-2026-97990 is a high-severity vulnerability in Linux, published on 25 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:

vdpa_sim_net: check TX pull result before RX copy

vringh_iov_pull_iotlb() returns a signed byte count.  A failed TX pull is
currently added to the unsigned byte counter and then passed as a size_t
length to receive_filter() and vringh_iov_push_iotlb().  A negative error
can therefore become a large length in the RX path.

Handle non-positive pull results before every length use.  Count the TX
error and complete the consumed TX descriptor with zero bytes.

I found this bug myself, though the patch was written with AI assistance.

## Which versions are affected by CVE-2026-97990?


## How do I fix CVE-2026-97990?

Apply the vendor's patch.

## Is CVE-2026-97990 being exploited?

There is no known exploitation of CVE-2026-97990 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97990 and fix it if it is affected.

What it is: CVE-2026-97990 is a high-severity vulnerability in Linux, published on 25 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-2026-97990 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-2026-97990/ (Markdown: https://insights.sbomify.com/CVE-2026-97990/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97990
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97990
- OSV: https://osv.dev/vulnerability/CVE-2026-97990

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97990/
Summaries are generated and may contain mistakes; the official description above is the record.