# CVE-2026-89539: SUNRPC: reject duplicate CREDS_VALUE options

> A remote attacker can cause a memory leak in the Linux kernel SUNRPC module by sending duplicate CREDS_VALUE options, leading to resource exhaustion.

- **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:** 21 Oct 2026
- **Also known as:** AZL-100665, BELL-CVE-2026-89539, DEBIAN-CVE-2026-89539, GHSA-j7j8-rmpg-46w5, UBUNTU-CVE-2026-89539

## What is CVE-2026-89539?

CVE-2026-89539 is a memory corruption 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:

SUNRPC: reject duplicate CREDS_VALUE options

gssx_dec_option_array() walks the wire-supplied option array and, for
every entry whose name matches CREDS_VALUE, calls
gssx_dec_linux_creds() on the same struct svc_cred. That helper
unconditionally installs a fresh groups_alloc() result into
creds->cr_group_info without releasing whatever pointer was already
there:

    for (i = 0; i < count; i++) {
        ... decode name ...
        if (length == sizeof(CREDS_VALUE) &&
            memcmp(p, CREDS_VALUE, sizeof(CREDS_VALUE)) == 0) {
            err = gssx_dec_linux_creds(xdr, creds);
            ...
        }
    }

A reply that carries two CREDS_VALUE entries therefore overwrites
cr_group_info on the second iteration and orphans the group_info
allocated by the first call. The earlier free_creds path only
releases the last cr_group_info via free_svc_cred(), so the first
allocation's refcount stays at one and its kvmalloc-backed storage
is leaked. No in-tree caller of gssp_accept_sec_context_upcall()
expects more than one CREDS_VALUE per reply.

Fix by tracking whether a CREDS_VALUE option has already been
decoded and returning -EINVAL on any subsequent match, so the
free_creds path releases the single group_info that was installed.

## Which versions are affected by CVE-2026-89539?


## How do I fix CVE-2026-89539?

Apply the vendor's patch.

## Is CVE-2026-89539 being exploited?

There is no known exploitation of CVE-2026-89539 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89539 and fix it if it is affected.

What it is: CVE-2026-89539 is a memory corruption 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-2026-89539 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-2026-89539/ (Markdown: https://insights.sbomify.com/CVE-2026-89539/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89539
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89539
- OSV: https://osv.dev/vulnerability/CVE-2026-89539

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89539/
Summaries are generated and may contain mistakes; the official description above is the record.