Linux Kernel up to 6.18.50/7.2.3 nfsd nfsd_file_dispose_list_delayed use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$5k-$25k0.00+

Summaryinfo

A vulnerability identified as very critical has been detected in Linux Kernel up to 6.18.50/7.2.3. This vulnerability affects the function nfsd_file_dispose_list_delayed of the component nfsd. Performing a manipulation results in use after free. This vulnerability is cataloged as CVE-2026-89682. It is possible to initiate the attack remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.50/7.2.3. It has been classified as very critical. This affects the function nfsd_file_dispose_list_delayed of the component nfsd. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-89682 since 09/11/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/12/2026).

Upgrading to version 6.18.51, 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch ba0ee9e04b7a0356c28d5a2fe445db675d24e572/cadc9036d5a8209f89e7026ddba7cfb1c716b03c/bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

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Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.51/7.2.4/7.3-rc1
Patch: ba0ee9e04b7a0356c28d5a2fe445db675d24e572/cadc9036d5a8209f89e7026ddba7cfb1c716b03c/bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4

Timelineinfo

09/11/2026 CVE reserved
09/12/2026 +1 days Advisory disclosed
09/12/2026 +0 days VulDB entry created
09/12/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89682 (🔒)
GCVE (CVE): GCVE-0-2026-89682
GCVE (VulDB): GCVE-100-402999

Entryinfo

Created: 09/12/2026 02:33
Changes: 09/12/2026 02:33 (59)
Complete: 🔍
Cache ID: 216::103

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