Linux Kernel up to 6.18.49/7.2.3 nfsd nfs4xdr.c notify_change nseconds input validation

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
9.5	$5k-$25k	0.00+

Summaryinfo

A vulnerability, which was classified as very critical, was found in Linux Kernel up to 6.18.49/7.2.3. Affected is the function notify_change of the file nfs4xdr.c of the component nfsd. Executing a manipulation of the argument nseconds can lead to input validation. The identification of this vulnerability is CVE-2026-89701. The attack may be launched remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as very critical was found in Linux Kernel up to 6.18.49/7.2.3. This vulnerability affects the function notify_change of the file nfs4xdr.c of the component nfsd. The manipulation of the argument nseconds with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: nfsd: validate nseconds in TIME_DELEG decode paths The xdrgen-based TIME_DELEG_ACCESS and TIME_DELEG_MODIFY decode arms store a raw uint32_t nseconds directly into tv_nsec without enforcing nseconds < NSEC_PER_SEC. The legacy nfsd4_decode_nfstime4 has this check but the TIME_DELEG paths do not. A malformed timespec can propagate through notify_change() to disk. Add range checks in both nfs4xdr.c (SETATTR path) and nfs4callback.c (CB_GETATTR path).

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2026-89701 since 09/11/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 09/11/2026).

Upgrading to version 6.18.50, 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch 7e7b93da7fa2e77f977096251899d1410986adf6/5eb489831a9fd4754f4baf26e6989efb66ce104c/0f4a767340fad392bd656115b8752005518c9065 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 6.18.40
• 6.18.41
• 6.18.42
• 6.18.43
• 6.18.44
• 6.18.45
• 6.18.46
• 6.18.47
• 6.18.48
• 6.18.49
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

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

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Input validation
CWE: CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

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

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.50/7.2.4/7.3-rc1
Patch: 7e7b93da7fa2e77f977096251899d1410986adf6/5eb489831a9fd4754f4baf26e6989efb66ce104c/0f4a767340fad392bd656115b8752005518c9065

Timelineinfo

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

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89701 (🔒)
GCVE (CVE): GCVE-0-2026-89701
GCVE (VulDB): GCVE-100-402544

Entryinfo

Created: 09/11/2026 22:09
Changes: 09/11/2026 22:09 (61)
Complete: 🔍
Cache ID: 216::103

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Discussion

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