VulnerabilityPublished 23 Oct 2026

CVE-2026-98996: Linux kernel · fs: don't silently unmount busy mounts

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in bf2c8dec26fb792876b5e9bde7030c45d8be3908 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

Severity

High

Rated High 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 bf2c8dec26fb792876b5e9bde7030c45d8be3908, a210ac218c307513d43e98a08f23c2dfbeeebc2f, 6857e209015f95be7a8f19a9cd5dac345b9b9859 +5

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 to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=4.1.43 <4.2 >=4.4.78 <4.5 >=4.9.39 <4.10 >=4.11.12 <4.12 >=4.12.3 <4.13	Fixed in bf2c8dec26fb792876b5e9bde7030c45d8be3908 a210ac218c307513d43e98a08f23c2dfbeeebc2f 6857e209015f95be7a8f19a9cd5dac345b9b9859 4.13 4.12 4.10 4.5 4.2
LinuxLinux	Affected =4.13	Fixed in–

AI-suggested

The vulnerability has been fixed in Linux kernel versions 4.2, 4.5, 4.10, 4.12, and 4.13. Users and administrators should upgrade to these or later kernel versions to remediate the issue. No other mitigation or workaround is indicated in the vendor advisory.

Description

CVE-2026-98996 is a Linux kernel vulnerability where the system may silently unmount busy mounts during propagation, causing mounts still in use to be detached. This occurs due to propagate_mount_busy() not properly checking references on certain mount copies, allowing synchronous unmounts to succeed incorrectly. The issue affects multiple Linux kernel versions from 4.1.43 up to and including 4.13. The vulnerability has been fixed in Linux kernel versions 4.2, 4.5, 4.10, 4.12, and 4.13.

Impact

A mount point that is still in use can be silently unmounted, potentially causing unexpected behavior in containerized environments or systems relying on mount propagation. This could lead to resource inconsistencies or failures in applications depending on those mounts. There is no indication of remote code execution or privilege escalation from the provided data.

Summary

The vulnerability arises from propagate_mount_busy() in the Linux kernel not correctly verifying whether mounts are busy before unmounting them during mount propagation. Changes in mount propagation logic introduced by commits 1064f874abc0 and 99b19d16471e caused propagate_umount() to unmount more mounts than before, but propagate_mount_busy() was not updated accordingly. This leads to situations where a synchronous unmount can succeed on mounts still in use, particularly in container environments sharing mount trees with the host. The fix involves updating propagate_mount_busy() to perform the same checks as propagate_umount(), ensuring mounts with children or references are not unmounted prematurely.

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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