Linux Kernel up to 6.12.108/6.18.49/7.2.3 nfsd nfsd4_release_compoundargs 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-$25k0.41+

Summaryinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 6.12.108/6.18.49/7.2.3. The impacted element is the function nfsd4_release_compoundargs of the component nfsd. This manipulation causes use after free. This vulnerability appears as CVE-2026-89690. The attack may be initiated remotely. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as very critical was found in Linux Kernel up to 6.12.108/6.18.49/7.2.3. Affected by this vulnerability is the function nfsd4_release_compoundargs of the component nfsd. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: nfsd: defer vfree of compound ops to fix rpc_status UAF The rpc_status netlink dumpit walks every in-flight svc_rqst under rcu_read_lock and, for NFSv4 requests, reads opnums out of args->ops[]. But args->ops is a separate vmalloc buffer freed synchronously by vfree() in nfsd4_release_compoundargs() at the end of every compound. The dumpit's rcu_read_lock pins the svc_rqst struct itself (freed via kfree_rcu), but nothing defers the vfree of the ops buffer across the RCU grace period. A concurrent compound completion can therefore free the buffer while the dumpit is reading it — a use-after-free on vmalloc memory. The trailing seqcount recheck (smp_load_acquire of rq_status_counter) cannot undo a load that already retired against freed memory. Fix by replacing vfree(args->ops) with kvfree_rcu_mightsleep(), which defers the free until after an RCU grace period. This makes the existing rcu_read_lock in the dumpit sufficient to protect the read. The tradeoff is that completed compound ops buffers (up to 200 * sizeof(struct nfsd4_op)) persist in memory slightly longer, across one grace period, before being reclaimed.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-89690 since 09/11/2026. The exploitation appears to be easy. The attack can be launched 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 6.12.109, 6.18.50, 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch 48f72aff24f7a7329209dc6cbc27c869f3e3595c/6703199f4d7e7f37d6a726a849eb358e8fae72fb/19413ccc45070a7270b9e25c2a258daf7f91de42/fca26a3fc19ed02278aa2a150af82d43db0302cb is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

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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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💳💳💳💳💳💳
💳💳💳💳💳💳
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 6.12.109/6.18.50/7.2.4/7.3-rc1
Patch: 48f72aff24f7a7329209dc6cbc27c869f3e3595c/6703199f4d7e7f37d6a726a849eb358e8fae72fb/19413ccc45070a7270b9e25c2a258daf7f91de42/fca26a3fc19ed02278aa2a150af82d43db0302cb

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-2026-89690 (🔒)
GCVE (CVE): GCVE-0-2026-89690
GCVE (VulDB): GCVE-100-403003

Entryinfo

Created: 09/12/2026 02:35
Changes: 09/12/2026 02:35 (59)
Complete: 🔍
Cache ID: 216::103

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