VulnerabilityPublished 23 Oct 2026

CVE-2026-98979: Linux kernel · namespace: refuse an automount below a mount that is in no namespace

Source GCVE Database

Authoritative record:CVE-2026-98979· High

Not known to be exploited · fixed in ba985ce08471c555af2a2fbe217c1bc2e72a6d8c : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

Severity

High

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 ba985ce08471c555af2a2fbe217c1bc2e72a6d8c, 776e20e4fdc23c23687b511ffdc80047878049d3, 494c57572d2d5bc2839553ed41aabe92ed0f587c +2

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.

ghsa-xhgj-mp6g-fw2x

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ df820f8de4e481222b17f9bcee7b909ae8167529, < ba985ce08471c555af2a2fbe217c1bc2e72a6d8c	Fixed in ba985ce08471c555af2a2fbe217c1bc2e72a6d8c
LinuxLinux	Affected ≥ df820f8de4e481222b17f9bcee7b909ae8167529, < 776e20e4fdc23c23687b511ffdc80047878049d3	Fixed in 776e20e4fdc23c23687b511ffdc80047878049d3
LinuxLinux	Affected ≥ df820f8de4e481222b17f9bcee7b909ae8167529, < 494c57572d2d5bc2839553ed41aabe92ed0f587c	Fixed in 494c57572d2d5bc2839553ed41aabe92ed0f587c
LinuxLinux	Affected ≥ df820f8de4e481222b17f9bcee7b909ae8167529, < 95fb7c259b86f5521f04973040ad492f2bef6f82	Fixed in 95fb7c259b86f5521f04973040ad492f2bef6f82
LinuxLinux	Affected ≥ df820f8de4e481222b17f9bcee7b909ae8167529, < 35f2013f83ef16f9f0331c4c3a8e8d161580d574	Fixed in 35f2013f83ef16f9f0331c4c3a8e8d161580d574
LinuxLinux	Affected =5.8	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: namespace: refuse an automount below a mount that is in no namespace It's possible to add autmounts even when the parent mount isn't in the mount namespace of the caller. The only requirement we have is that the parent mount namespace must not be NULL, i.e., unmounted. Problem is that clone_private_mount() has MNT_NS_INTERNAL which makes that trivially true. So that passes the test and attach_recursive_mnt() accepts that as a mount point and funny enough, count_mounts() dereferences MNT_NS_INTERNAL. The problem is it is an error pointer... So we can reach this in userspace via fanotify. A filesystem mark on the lower filesystem of an overlay reports paths on the layer clone and reading the event hands out a descriptor on it. For example with debugfs as the lower layer it goes kaboom: openat(evfd, "tracing", O_DIRECTORY) Oops: general protection fault KASAN: null-ptr-deref in range [0x1d0-0x1d7] RIP: 0010:count_mounts+0x35/0x200 attach_recursive_mnt finish_automount And since that sleeping beauty happens under namespace_sem held for writing every mount operation on the system blocks from then on. Congrats. Use is_mounted() instead which rejects unmounted and internal mounts alike. The open fails with EINVAL just as it did before clone_private_mount() used MNT_NS_INTERNAL.

References

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