High severity · published Sep 11, 2026
CVE-2026-89682
nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net
8.1
CVSS
0.6%
EPSS
No
On KEV
Description
In the Linux kernel, the following vulnerability has been resolved:
nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net
nfsd_file_dispose_list_delayed() defers fput() to nfsd service threads
via a per-net freeme queue, preventing the shrinker and GC worker from
bearing the cost of closing files (see ffb402596147). However, the
queue lives in a separately-allocated struct nfsd_fcache_disposal that
is freed by nfsd_free_fcache_disposal_net() during per-net teardown.
The global shrinker, laundrette, and fsnotify callbacks can still be
inside nfsd_file_dispose_list_delayed() dereferencing that pointer,
causing a use-after-free.
Inline the spinlock and freeme list directly into struct nfsd_net (as
fcache_dispose_lock and fcache_dispose_list), eliminating the separately
allocated struct nfsd_fcache_disposal entirely. These fields now have
the same lifetime as the net namespace itself, so there is no dangling
pointer to chase.
nfsd_file_cache_start_net() now just initializes the inline fields and
cannot fail due to allocation. nfsd_file_cache_shutdown_net() drains
the inline list directly instead of freeing a separate struct. The
alloc/free helpers are removed.
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 46% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Linux · Linux
1463b38e7cf34d4cc60f41daff459ad807b2e408 before e6c3a43d0a41f03abae3764fc82a59369360c7e0; 1463b38e7cf34d4cc60f41daff459ad807b2e408 before 9c8ac7c2b9b150e13b7ad0d0fae54f17747dce67; 1463b38e7cf34d4cc60f41daff459ad807b2e408 before ba0ee9e04b7a0356c28d5a2fe445db675d24e572; 1463b38e7cf34d4cc60f41daff459ad807b2e408 before cadc9036d5a8209f89e7026ddba7cfb1c716b03c; 1463b38e7cf34d4cc60f41daff459ad807b2e408 before bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4; e8f923e1e9fcc0832a12c8a2461792e5a9544c03; +4 more · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-89682
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-89682
git.kernel.org
https://git.kernel.org/stable/c/9c8ac7c2b9b150e13b7ad0d0fae54f17747dce67
git.kernel.org
https://git.kernel.org/stable/c/ba0ee9e04b7a0356c28d5a2fe445db675d24e572
git.kernel.org
https://git.kernel.org/stable/c/bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4
git.kernel.org
https://git.kernel.org/stable/c/cadc9036d5a8209f89e7026ddba7cfb1c716b03c
git.kernel.org
https://git.kernel.org/stable/c/e6c3a43d0a41f03abae3764fc82a59369360c7e0
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