High severity · published Sep 11, 2026
CVE-2026-89547
SUNRPC: Check svc pool percpu counter allocation
8.1
CVSS
0.6%
EPSS
No
On KEV
Description
In the Linux kernel, the following vulnerability has been resolved:
SUNRPC: Check svc pool percpu counter allocation
__svc_create() initializes three per-pool percpu_counter stats and
ignores every return value. On SMP, percpu_counter_init() fails when
__alloc_percpu_gfp() cannot satisfy the allocation, leaving the failed
counter with fbc->counters == NULL and its embedded raw_spinlock_t,
list_head, and count never initialized. __svc_create() returns the
half-constructed svc_serv to nfsd, lockd, or the NFS callback service
anyway.
Once that service is live, the hot-path increments in
svc_xprt_enqueue(), svc_handle_xprt(), and
svc_pool_wake_idle_thread() reach a counter whose backing pointer is
NULL. The pointer is a per-cpu offset, so the access does not fault:
it resolves to offset zero of the current CPU's per-cpu area and
silently corrupts whatever variable lives there. A
/proc/fs/nfsd/pool_stats read walks the same NULL per-cpu storage and
returns garbage, and on CONFIG_DEBUG_SPINLOCK or lockdep it splats on
the never-initialized lock.
Creating the broken service requires a percpu allocation failure during
RPC server startup, so it is reachable only by a local administrator
under memory pressure or fault injection; a remote peer cannot induce
the bad state on its own.
Check each percpu_counter_init() return value in __svc_create() and
fail when an allocation fails, unwinding the counters already set up
in the current pool and in every pool initialized before it. A
discrete percpu_counter_destroy() per counter at teardown frees each
per-cpu allocation exactly once.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 47% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Linux · Linux
ccf08bed6e7a80519569456edd2ea21b7b1701c6 before 57ac7d899409b0a9b768cf417e3bb86bcca3d4c6; ccf08bed6e7a80519569456edd2ea21b7b1701c6 before 3a2b7649de76376a69f1d3ed2a539fb15907cd4d; ccf08bed6e7a80519569456edd2ea21b7b1701c6 before bd1ef2cfb44d72b7aa6943e87b206eb0e30fbd0c; ccf08bed6e7a80519569456edd2ea21b7b1701c6 before b541a15046976e481618726cc23db0fb22d576db; ccf08bed6e7a80519569456edd2ea21b7b1701c6 before 43e11e164704dde975c9edb370de1a06bec67270; 6.3 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-89547
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-89547
git.kernel.org
https://git.kernel.org/stable/c/3a2b7649de76376a69f1d3ed2a539fb15907cd4d
git.kernel.org
https://git.kernel.org/stable/c/43e11e164704dde975c9edb370de1a06bec67270
git.kernel.org
https://git.kernel.org/stable/c/57ac7d899409b0a9b768cf417e3bb86bcca3d4c6
git.kernel.org
https://git.kernel.org/stable/c/b541a15046976e481618726cc23db0fb22d576db
git.kernel.org
https://git.kernel.org/stable/c/bd1ef2cfb44d72b7aa6943e87b206eb0e30fbd0c
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