VulnerabilityPublished 23 Oct 2026

CVE-2026-98986: Linux kernel · namespace: remove the fsnotify marks of a mount namespace in process context

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in 888363d74c3b5d32e2accf217add70f8b38e0e2b : update Linux kernel when convenient.

Data as of 26 Oct 2026, 17:30 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 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 888363d74c3b5d32e2accf217add70f8b38e0e2b, 9e820a6becdd955a04adbedfd767253a47eedd9e, 1a116222acdcc1bc1a8350727ae6f28907d44594

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 888363d74c3b5d32e2accf217add70f8b38e0e2b, 9e820a6becdd955a04adbedfd767253a47eedd9e or 1a116222acdcc1bc1a8350727ae6f28907d44594.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ bf630c40164162ba1d3933c2f5e3397d083e0948, < 888363d74c3b5d32e2accf217add70f8b38e0e2b	Fixed in 888363d74c3b5d32e2accf217add70f8b38e0e2b
LinuxLinux	Affected ≥ bf630c40164162ba1d3933c2f5e3397d083e0948, < 9e820a6becdd955a04adbedfd767253a47eedd9e	Fixed in 9e820a6becdd955a04adbedfd767253a47eedd9e
LinuxLinux	Affected ≥ bf630c40164162ba1d3933c2f5e3397d083e0948, < 1a116222acdcc1bc1a8350727ae6f28907d44594	Fixed in 1a116222acdcc1bc1a8350727ae6f28907d44594
LinuxLinux	Affected =6.15	Fixed in–

AI-suggested

A fix is available in Linux kernel commits 888363d74c3b5d32e2accf217add70f8b38e0e2b, 9e820a6becdd955a04adbedfd767253a47eedd9e, and 1a116222acdcc1bc1a8350727ae6f28907d44594. Users should upgrade to a patched kernel version that includes these commits. No additional mitigation is required once patched.

Description

A vulnerability in the Linux kernel's mount namespace handling allows improper removal of fsnotify marks in an invalid context, causing kernel locking issues. This occurs when the last passive reference of a mount namespace is dropped and its fanotify marks are removed in a softirq context instead of process context, potentially leading to kernel bugs. The flaw affects Linux kernel version 6.15 and has been fixed in later commits.

Impact

This vulnerability can cause kernel bugs related to improper locking and sleeping in invalid contexts, potentially leading to system instability or crashes. It requires root privileges in a user namespace and control over a mount namespace to exploit. There is no indication of remote exploitation or privilege escalation beyond user namespace root. No known exploits in the wild have been reported.

Summary

The vulnerability involves the Linux kernel's mount namespace release process where fsnotify marks are removed in an invalid context (softirq) rather than process context. Specifically, mnt_ns_release() removes fanotify marks while holding mutexes and spinlocks safely in process context, but mnt_ns_tree_remove() defers removal to call_rcu(), which runs in softirq context. This leads to a BUG due to sleeping functions called from invalid context and lockdep warnings about connector locks taken in softirq. An attacker with root in a user namespace can add a fanotify mark on a mount namespace they own and cause the namespace to be freed with marks still present, triggering the issue. The fix moves mark removal to free_mnt_ns(), which runs in process context after the last active reference is gone, preventing marks from existing after namespace release.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 09:55 UTC

Technical details

References

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