VulnerabilityPublished 19 Jul 2026Updated 17 Aug 2026

CVE-2026-64159: Linux kernel · netfs: Fix zeropoint update where i_size > remote_i_size

Source GCVE Database

Authoritative record:CVE-2026-64159

Not known to be exploited · CVSS 5.5 Medium · fixed in f706e3889ff75877ecb3abae5ad667dbc990331e : update Linux kernel when convenient.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score

5.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f706e3889ff75877ecb3abae5ad667dbc990331e, 4543a4d737944134a1394afe797622546fbcc98a, 6.11 +2

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-hrh3-6x34-5fxf

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=6.10.8 <6.11	Fixed in f706e3889ff75877ecb3abae5ad667dbc990331e 4543a4d737944134a1394afe797622546fbcc98a 6.11 5cd5207de519ef0c085f4f559adf5eefcb4c5202 5afc2d9b86bed2e4d9e1ba467790cbc793223f98
LinuxLinux	Affected =6.11	Fixed in–

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel netfs subsystem. Users and administrators should apply the official Linux kernel updates that include this fix. Since this is a kernel-level issue, upgrading to a patched kernel version is the recommended remediation. Patch status is not explicitly stated in the provided data; therefore, check the official Linux kernel advisories or distribution security updates for the exact fixed versions and apply them accordingly.

Description

A vulnerability in the Linux kernel's netfs subsystem involving incorrect update of the zero point when the local file size (i_size) exceeds the remote server's file size (remote_i_size) has been resolved. The flaw caused the zero point to be set incorrectly, potentially leading to read errors or incorrect file data handling. The zero point is critical for determining where the server will return zeros instead of actual data, optimizing read operations. This issue was identified through extensive filesystem testing and affects the netfs_release_folio() function's handling of uncommitted data in the pagecache. The vulnerability has a medium severity with a CVSS score of 5.5 and does not impact confidentiality or integrity but affects availability.

Impact

This vulnerability affects the availability of file data in the netfs filesystem by causing incorrect zero point updates, which can lead to read errors or short reads when accessing files with uncommitted local changes beyond the server's EOF. There is no impact on confidentiality or integrity. The CVSS score of 5.5 reflects a medium severity with local attack vector, low complexity, and requiring privileges. No known active exploitation has been reported.

Summary

The Linux kernel netfs subsystem had a vulnerability where netfs_release_folio() incorrectly updated the zero point based on the local file size (i_size) rather than the remote server's file size (remote_i_size). This discrepancy occurs when there is uncommitted data in the pagecache beyond the folio being released, and the server's end-of-file (EOF) is within that folio (i_size > remote_i_size). The zero point should be limited to remote_i_size to correctly reflect the server's EOF, as i_size reflects local cache updates not yet written to the server. Incorrect zero point updates can cause read-gaps and short reads, potentially impacting file availability. The issue was discovered using the fsx test suite on CIFS with default cache options and has been fixed in the Linux kernel netfs code. No known exploits are reported in the wild.

References

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