# CVE-2026-89529: svcrdma: Reject oversized Read segments at decode time

> An attacker can cause a resource leak and potential denial of service in the Linux kernel by sending oversized RPC/RDMA Read segments.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-89529, GHSA-4fgg-mw2q-x784, UBUNTU-CVE-2026-89529

## What is CVE-2026-89529?

CVE-2026-89529 is a denial of service vulnerability in Linux, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

svcrdma: Reject oversized Read segments at decode time

The RPC/RDMA Read list decoder stores wire-supplied segment
lengths without validation. xdr_count_read_segments() checks
4-byte alignment for non-zero position values but does not
cap the segment length.

An oversized rs_length reaches svc_rdma_build_read_segment(),
which derives nr_bvec from it and can drive a large dynamic
bvec allocation before verifying that enough rq_pages remain.
If the post-allocation page-overrun guard fires, the freshly
acquired rw context is not returned, leaking the resource.

Reject any segment whose length exceeds the receive context's
page budget during Read list decoding, consistent with how
xdr_check_write_chunk() bounds Write segment counts against
rc_maxpages. Also return the rw context on the existing
post-allocation overrun path in svc_rdma_build_read_segment(),
keeping that defensive guard balanced.

## Which versions are affected by CVE-2026-89529?


## How do I fix CVE-2026-89529?

Apply the vendor's patch.

## Is CVE-2026-89529 being exploited?

There is no known exploitation of CVE-2026-89529 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89529 and fix it if it is affected.

What it is: CVE-2026-89529 is a denial of service vulnerability in Linux, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-89529 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-2026-89529/ (Markdown: https://insights.sbomify.com/CVE-2026-89529/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89529
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89529
- OSV: https://osv.dev/vulnerability/CVE-2026-89529

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89529/
Summaries are generated and may contain mistakes; the official description above is the record.