# CVE-2026-90417: RDMA/cxgb4: Fix dereg_skb leak and double free in write_tpt_entry()

> A double free and memory leak in the Linux kernel's cxgb4 RDMA driver can lead to system crashes or potential code execution.

- **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:** 17 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-102695, BELL-CVE-2026-90417, DEBIAN-CVE-2026-90417, GHSA-ccpx-w89w-v2mx, UBUNTU-CVE-2026-90417

## What is CVE-2026-90417?

CVE-2026-90417 is an 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/cxgb4: Fix dereg_skb leak and double free in write_tpt_entry()

When the device is in the fatal error state, write_tpt_entry() returns -EIO
before handing the caller's preallocated skb to the transmit path; its
allocation-failure returns do the same. c4iw_dereg_mr() ignores the error
and frees mhp, leaking mhp->dereg_skb. c4iw_get_dma_mr() instead frees the
skb a second time after dereg_mem() already consumed it, a double free.

Make write_tpt_entry() the sole owner of a non-NULL skb, freeing it on
every return preceding handoff to c4iw_ofld_send(): fatal error, tpt and
stag allocation failure. c4iw_ofld_send() consumes the skb on success and
error alike, so drop the redundant kfree_skb() in c4iw_get_dma_mr() after
dereg_mem().

## Which versions are affected by CVE-2026-90417?


## How do I fix CVE-2026-90417?

Apply the vendor's patch.

## Is CVE-2026-90417 being exploited?

There is no known exploitation of CVE-2026-90417 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90417 and fix it if it is affected.

What it is: CVE-2026-90417 is an 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-2026-90417 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-2026-90417/ (Markdown: https://insights.sbomify.com/CVE-2026-90417/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90417
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90417
- OSV: https://osv.dev/vulnerability/CVE-2026-90417

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90417/
Summaries are generated and may contain mistakes; the official description above is the record.