CVE-2026-89539: Linux kernel · SUNRPC: reject duplicate CREDS_VALUE options
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in f615b884310bf82d0014e3b5a92eb9aa88146685 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 13:47 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in f615b884310bf82d0014e3b5a92eb9aa88146685, 9d94f046b23de0f77849ea69133063c949297e30, 7a1d0501cbb962beba23377035d667bf3c1726ee +2
Exploitation evidence
Disclosed: evidence found.
CVE published 11 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in– |
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.
References
- git.kernel.org/stable/c/4b5ebb4f91a6152a0f7b1253f701197e5710d4da (opens in a new tab)
- git.kernel.org/stable/c/f615b884310bf82d0014e3b5a92eb9aa88146685 (opens in a new tab)
- git.kernel.org/stable/c/7a1d0501cbb962beba23377035d667bf3c1726ee (opens in a new tab)
- git.kernel.org/stable/c/9d94f046b23de0f77849ea69133063c949297e30 (opens in a new tab)
- git.kernel.org/stable/c/2e4ce62385c1b8a887c5370af058ac7b52a8eaf9 (opens in a new tab)