# CVE-2026-90415: RDMA/cxgb4: free STAG index when TPT entry write fails

> A resource leak in the Linux kernel RDMA driver allows attackers to exhaust STAG indices, causing denial of service.

- **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:** 19 Oct 2026
- **Also known as:** AZL-102716, BELL-CVE-2026-90415, DEBIAN-CVE-2026-90415, GHSA-v598-vrqp-g6vj, UBUNTU-CVE-2026-90415

## What is CVE-2026-90415?

CVE-2026-90415 is a denial of service 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: free STAG index when TPT entry write fails

write_tpt_entry() allocates a new STAG index with c4iw_get_resource() and
bumps stats.stag.cur before programming the entry.  When
write_adapter_mem() fails, it returns the error without releasing the index
or reversing the statistic.  No MR is inserted into rhp->mrs, so
deregistration never reclaims it, leaking the index until device teardown.

Record whether this call allocated the index and, on a failed write, return
it to tpt_table and decrement stats.stag.cur.  Key the rollback on both the
write error and that flag, not the error alone: a non-reset update carries
a caller-owned STAG that this call did not allocate and must not free.

## Which versions are affected by CVE-2026-90415?


## How do I fix CVE-2026-90415?

Apply the vendor's patch.

## Is CVE-2026-90415 being exploited?

There is no known exploitation of CVE-2026-90415 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90415 and fix it if it is affected.

What it is: CVE-2026-90415 is a denial of service 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-2026-90415 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-2026-90415/ (Markdown: https://insights.sbomify.com/CVE-2026-90415/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90415
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90415
- OSV: https://osv.dev/vulnerability/CVE-2026-90415

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90415/
Summaries are generated and may contain mistakes; the official description above is the record.