VulnerabilityPublished 18 Oct 2026

CVE-2026-98683: Linux kernel · smb: client: flush dirty data before zeroing a range

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in e8ba21c7e6ef3d4cb617858760673877b2e4a2bb : update Linux kernel when convenient.

Data as of 26 Oct 2026, 12:55 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD

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 e8ba21c7e6ef3d4cb617858760673877b2e4a2bb, cecf4114069fc19629d284710fd783d56bbca862, 8f8d32c1044f70e46e87550e039a15ff20a4b21c +3

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 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.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=6.1.110 <6.2 >=6.6.51 <6.7 >=6.10.10 <6.11	Fixed in e8ba21c7e6ef3d4cb617858760673877b2e4a2bb cecf4114069fc19629d284710fd783d56bbca862 8f8d32c1044f70e46e87550e039a15ff20a4b21c 6.11 6.7 6.2
LinuxLinux	Affected =6.11	Fixed in–

AI-suggested

A fix is available in Linux kernel versions 6.2, 6.7, 6.11, and later. Users should upgrade to these or later kernel versions to remediate the issue. No additional mitigation steps are indicated.

Description

A vulnerability in the Linux kernel SMB client implementation allowed stale data to be read from zeroed file ranges due to improper flushing of dirty data before zeroing. This flaw was fixed by ensuring dirty data is always flushed before invalidating the page cache and issuing zero-range commands to the server. The issue affected multiple Linux kernel versions prior to 6.2, 6.7, 6.11, and the exact 6.11 release.

Impact

This vulnerability could cause clients to read stale data in file ranges that were expected to be zeroed, potentially leading to data integrity issues or incorrect application behavior when accessing SMB shares via the Linux kernel SMB client. There is no indication of remote code execution or privilege escalation. No known exploits in the wild have been reported.

Summary

The Linux kernel SMB client function smb3_zero_range() emulates the FALLOC_FL_ZERO_RANGE operation by invalidating the page cache over a target range and issuing FSCTL_SET_ZERO_DATA to the SMB server. Previously, dirty data was flushed only if the zeroed range reached or extended beyond EOF. For zero ranges fully inside the file (not reaching EOF), dirty data was not flushed, allowing stale data from dirty folios to be written back after zeroing, thus refilling the zeroed range with old data. The fix unconditionally flushes and waits for dirty data in the range before invalidating the page cache and issuing FSCTL_SET_ZERO_DATA, aligning with the approach used in smb3_punch_hole(). This resolves the issue of reading stale data where zeroed data was expected, as observed against Windows Server.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 10:02 UTC

Technical details

References

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