# CVE-2026-89539

## Summary

- **CVE ID:** CVE-2026-89539
- **Severity:** UNKNOWN
- **CVSS Score:** 0
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 16, 2026

## 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.

## Affected Products

- Linux — Linux (1d658336b05f8697d6445834f8867f8ad5e4f735)
- Linux — Linux (3.10)
- Linux — Linux (0)
- Linux — Linux (6.12.109)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)

## References

- [CNA](https://git.kernel.org/stable/c/f615b884310bf82d0014e3b5a92eb9aa88146685)
- [CNA](https://git.kernel.org/stable/c/7a1d0501cbb962beba23377035d667bf3c1726ee)
- [CNA](https://git.kernel.org/stable/c/9d94f046b23de0f77849ea69133063c949297e30)
- [CNA](https://git.kernel.org/stable/c/2e4ce62385c1b8a887c5370af058ac7b52a8eaf9)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.17%
- **EPSS Percentile:** 6.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._