VulnerabilityPublished 23 Oct 2026Updated 26 Oct 2026

CVE-2026-98901: Linux kernel · ksmbd: fix lease break and ack state handling

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in fba4653a0b4dc2f6d42600abe21fb326292f70ff : update Linux kernel when convenient.

Data as of 26 Oct 2026, 13:07 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in fba4653a0b4dc2f6d42600abe21fb326292f70ff, 5015191096db311759fef98769270336cd8b1324, 17699905a381621c1cee5b6528feb05acedc86a4 +1

Exploitation evidence

Disclosed: evidence found.
CVE published 23 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 Linux kernel to fba4653a0b4dc2f6d42600abe21fb326292f70ff, 5015191096db311759fef98769270336cd8b1324, 17699905a381621c1cee5b6528feb05acedc86a4 or 3251ea36df5eef58aa207fbee48849d89b922ea6.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, < fba4653a0b4dc2f6d42600abe21fb326292f70ff	Fixed in fba4653a0b4dc2f6d42600abe21fb326292f70ff
LinuxLinux	Affected ≥ e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, < 5015191096db311759fef98769270336cd8b1324	Fixed in 5015191096db311759fef98769270336cd8b1324
LinuxLinux	Affected ≥ e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, < 17699905a381621c1cee5b6528feb05acedc86a4	Fixed in 17699905a381621c1cee5b6528feb05acedc86a4
LinuxLinux	Affected ≥ e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, < 3251ea36df5eef58aa207fbee48849d89b922ea6	Fixed in 3251ea36df5eef58aa207fbee48849d89b922ea6
LinuxLinux	Affected =5.15	Fixed in–

AI-suggested

A fix is available and has been applied in specific Linux kernel commits. Users should update to the fixed versions identified by the commits fba4653a0b4dc2f6d42600abe21fb326292f70ff, 5015191096db311759fef98769270336cd8b1324, 17699905a381621c1cee5b6528feb05acedc86a4, and 3251ea36df5eef58aa207fbee48849d89b922ea6. Applying these updates will remediate the vulnerability.

Description

A vulnerability in the Linux kernel's ksmbd component related to lease break and acknowledgment state handling has been fixed. The issue involved improper handling of valid lease states containing WRITE_CACHING during lease breaks for writes and truncates, and incorrect processing of lease break acknowledgments against SMB2 protocol rules.

Impact

The vulnerability could lead to improper lease state handling in SMB file sharing, potentially causing data consistency issues or unexpected behavior during write and truncate operations under certain lease conditions. No known exploits in the wild have been reported.

Summary

CVE-2026-98901 addresses a flaw in the Linux kernel's ksmbd module where valid lease states with WRITE_CACHING were incorrectly skipped when breaking level-II/read leases for write and truncate operations. Additionally, lease break acknowledgments were not handled according to SMB2 protocol requirements, which mandate that the acknowledged state must be a subset of the server's break target. The fix ensures that the acknowledged state is applied directly and that the break remains pending if acknowledgments fail. This resolves potential inconsistencies in lease state management within the SMB server implementation in the Linux kernel.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 09:33 UTC

Technical details

References

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