# CVE-2026-90309: RDMA/erdma: Hold CQ references when processing EQ events

> A use-after-free vulnerability in the Linux kernel's erdma driver allows attackers to cause denial of service or execute code via race conditions during CQ destruction.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102878, BELL-CVE-2026-90309, DEBIAN-CVE-2026-90309, GHSA-p9h2-4fgm-97q7, UBUNTU-CVE-2026-90309

## What is CVE-2026-90309?

CVE-2026-90309 is a high-severity use after free vulnerability in Linux, published on 17 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:

RDMA/erdma: Hold CQ references when processing EQ events

EQ handlers look up CQs from dev->cq_xa and invoke CQ completion or
error callbacks outside the xarray lock. erdma_destroy_cq() can erase the
CQ from the xarray and free its queue buffer and doorbell record while a
previously scheduled EQ handler is still using the CQ.

Add a CQ refcount and take a reference under the xarray lock with
refcount_inc_not_zero(). Remove the CQ from the xarray before dropping
the destroy-path reference, then wait for in-flight EQ users before
releasing CQ resources.

## Which versions are affected by CVE-2026-90309?


## How do I fix CVE-2026-90309?

Apply the vendor's patch.

## Is CVE-2026-90309 being exploited?

There is no known exploitation of CVE-2026-90309 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90309 and fix it if it is affected.

What it is: CVE-2026-90309 is a high-severity use after free vulnerability in Linux, published on 17 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-2026-90309 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-2026-90309/ (Markdown: https://insights.sbomify.com/CVE-2026-90309/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90309
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90309
- OSV: https://osv.dev/vulnerability/CVE-2026-90309

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90309/
Summaries are generated and may contain mistakes; the official description above is the record.