CVE-2026-89539: Linux Vulnerability

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.

Metrics

EPSS Probability

0.17%

6.2th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 1d658336b05f8697d6445834f8867f8ad5e4f735, < 6207d7df96b3a7f507f0bfc8842b3760ee2fb1f8; >= 1d658336b05f8697d6445834f8867f8ad5e4f735, < 4904d61eb2e2bd484000725fd302b8f37b4fcf3a; >= 1d658336b05f8697d6445834f8867f8ad5e4f735, < 64b9ef369a6f723294613cb129e5f62c35429df5; >= 1d658336b05f8697d6445834f8867f8ad5e4f735, < 4b5ebb4f91a6152a0f7b1253f701197e5710d4da; >= 1d658336b05f8697d6445834f8867f8ad5e4f735, < f615b884310bf82d0014e3b5a92eb9aa88146685; >= 1d658336b05f8697d6445834f8867f8ad5e4f735, < 7a1d0501cbb962beba23377035d667bf3c1726ee; >= 1d658336b05f8697d6445834f8867f8ad5e4f735, < 9d94f046b23de0f77849ea69133063c949297e30; >= 1d658336b05f8697d6445834f8867f8ad5e4f735, < 2e4ce62385c1b8a887c5370af058ac7b52a8eaf9
Linux	Linux	3.10

References

Timeline

Published: Sep 11, 2026
Last Modified: Oct 30, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-89539?

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.

How severe is CVE-2026-89539?

Severity scoring for CVE-2026-89539 is pending analysis. The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.

How do I fix CVE-2026-89539?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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