VulnerabilityPublished 23 Oct 2026Updated 26 Oct 2026

CVE-2026-98897: Linux kernel · ksmbd: don't hold ci->m_lock while waiting for a lease break ack

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in 868c9038ffd4af39766d087f68c8f543a3f66635 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:00 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 868c9038ffd4af39766d087f68c8f543a3f66635, 27a9bc968d4ae809a3f5ca2f2b136856ee613cb4, 6.7

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 868c9038ffd4af39766d087f68c8f543a3f66635, 27a9bc968d4ae809a3f5ca2f2b136856ee613cb4 or 6.7.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=6.6.35 <6.7	Fixed in 868c9038ffd4af39766d087f68c8f543a3f66635 27a9bc968d4ae809a3f5ca2f2b136856ee613cb4 6.7
LinuxLinux	Affected =6.9	Fixed in–

AI-suggested

A fix for this vulnerability is available in Linux kernel version 6.7 and later. Users and administrators should upgrade affected systems to version 6.7 or apply the corresponding patches to resolve the issue. No additional mitigation actions are required beyond applying the official fix.

Description

A vulnerability in the Linux kernel's ksmbd component involves holding a mutex lock (ci->m_lock) while waiting for a lease break acknowledgment, causing a potential deadlock and long delays in lease break resolution. This issue affects versions from 6.6.35 up to but not including 6.7, and version 6.9. The problem arises when a conflicting open triggers a lease break, but the acknowledgment wait blocks due to lock contention, leading to a timeout of up to 35 seconds. The fix involves changing the locking strategy to avoid holding the lock during the wait, improving lease break handling and performance.

Impact

The vulnerability causes a deadlock scenario during lease break handling in ksmbd, resulting in lease break acknowledgments being delayed by up to 35 seconds. This delay can significantly degrade performance and responsiveness of SMB lease operations, as evidenced by test cases showing increased execution time from approximately 4 seconds to 78 seconds with leases enabled. There is no indication of remote code execution or privilege escalation. No known exploits in the wild have been reported.

Summary

The Linux kernel vulnerability CVE-2026-98897 concerns the ksmbd server's handling of lease break acknowledgments. When a client caches a read-handle lease and a conflicting open occurs, ksmbd breaks the lease and waits for an acknowledgment while holding the ci->m_lock read lock. The client, reacting by closing the deferred handle, attempts to acquire the write lock on ci->m_lock, causing a deadlock that resolves only after a 35-second timeout. This leads to significant delays in lease break processing, as demonstrated by extended test durations. The patch changes the approach by collecting target lease information while holding the lock, then releasing it before breaking the leases, thus preventing the deadlock and improving responsiveness. The fix is applied in Linux kernel version 6.7 and later.

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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