# CVE-2026-90423: RDMA/rxe: Fix UAF in ODP init error-handling path

> A use-after-free vulnerability in the Linux kernel's RDMA/rxe driver allows attackers to potentially execute code or escalate privileges via improper error handling in ODP initialization.

- **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:** BELL-CVE-2026-90423, DEBIAN-CVE-2026-90423, GHSA-vg4x-c29w-66xm, UBUNTU-CVE-2026-90423

## What is CVE-2026-90423?

CVE-2026-90423 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/rxe: Fix UAF in ODP init error-handling path

rxe_odp_mr_init_user() stores &umem_odp->umem in mr->umem before
calling rxe_odp_init_pages(). If rxe_odp_init_pages() fails,
rxe_odp_mr_init_user() releases umem_odp and returns an error.

rxe_reg_user_mr() then unwinds the error through rxe_cleanup(),
rxe_mr_cleanup(), ib_umem_release(mr->umem). There is an
IS_ERR_OR_NULL(umem) check at the start of ib_umem_release().
But since mr->umem is NOT reset to NULL in the error handling
path of rxe_odp_mr_init_user(), the check passes and it reads
already-freed fields like umem->is_dmabuf, causing UAF.

Fix the UAF by clearing mr->umem after releasing the failed
ODP umem so the MR cleanup path does not release it again.

## Which versions are affected by CVE-2026-90423?


## How do I fix CVE-2026-90423?

Apply the vendor's patch.

## Is CVE-2026-90423 being exploited?

There is no known exploitation of CVE-2026-90423 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90423 and fix it if it is affected.

What it is: CVE-2026-90423 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-2026-90423 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-2026-90423/ (Markdown: https://insights.sbomify.com/CVE-2026-90423/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90423
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90423
- OSV: https://osv.dev/vulnerability/CVE-2026-90423

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90423/
Summaries are generated and may contain mistakes; the official description above is the record.