Investigate in your agent.

Turn this advisory into a focused investigation. Ask your agent to check your project’s versions, explain the evidence, and suggest a compatible fix.

Your agent needs remote MCP support and access to https://cve.new/mcp.

Read the setup guide

Skip to content
cve.newCreate a CVE report
Check your stack
CVE-2026-98979

namespace: refuse an automount below a mount that is in no namespace

Products / packages Linux

Published

Share

Severity and exploitation

Not in CISA KEVNo CVSS score

KEV coverage does not rule out exploitation.

KEV checked 14/11/2026, 23:05:32 UTC

Severity

unknown

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Fix status not established

No structured fix or guidance is available here. Check the latest publisher advisory.

What this means

The Linux kernel has a vulnerability where an automount can be added below a mount that is in no namespace, potentially causing a general protection fault. The issue affects Linux kernel versions starting from 5.8. The vulnerability can be reached via fanotify in userspace.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

Linux · Linux

Linux

8 ranges
Linux version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

df820f8de4e481222b17f9bcee7b909ae8167529 → before d8c7f74adf5de78035d41aa33c8f71e12b3ca430

git versions

df820f8de4e481222b17f9bcee7b909ae8167529 → before c88546071d30417ab9e55821c83f4dc7756cff6f

git versions

df820f8de4e481222b17f9bcee7b909ae8167529 → before c98e74d73a3356ab00fc6bb9dec3c77da1ec1ce4

git versions

df820f8de4e481222b17f9bcee7b909ae8167529 → before 95fb7c259b86f5521f04973040ad492f2bef6f82

git versions

df820f8de4e481222b17f9bcee7b909ae8167529 → before 35f2013f83ef16f9f0331c4c3a8e8d161580d574

git versions

df820f8de4e481222b17f9bcee7b909ae8167529 → before 494c57572d2d5bc2839553ed41aabe92ed0f587c

git versions

df820f8de4e481222b17f9bcee7b909ae8167529 → before 776e20e4fdc23c23687b511ffdc80047878049d3

git versions

df820f8de4e481222b17f9bcee7b909ae8167529 → before ba985ce08471c555af2a2fbe217c1bc2e72a6d8c

git versions

unaffected

unknown

Other versions: unaffected

Linux · Linux

Linux

10 ranges
Linux version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

5.8

unaffected

0 → before 5.8

semver versions

5.10.273 → through 5.10.*

semver versions

5.15.224 → through 5.15.*

semver versions

6.1.191 → through 6.1.*

semver versions

6.6.160 → through 6.6.*

semver versions

6.12.113 → through 6.12.*

semver versions

6.18.57 → through 6.18.*

semver versions

7.2.11 → through 7.2.*

semver versions

7.3 → through *

original_commit_for_fix versions

unknown

Other versions: affected

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher 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

8 sources
git.kernel.org/stable/c/d8c7f74adf5de78035d41aa33c8f71e12b3ca430
Source referenceLinux
git.kernel.org/stable/c/c88546071d30417ab9e55821c83f4dc7756cff6f
Source referenceLinux
git.kernel.org/stable/c/c98e74d73a3356ab00fc6bb9dec3c77da1ec1ce4
Source referenceLinux
git.kernel.org/stable/c/95fb7c259b86f5521f04973040ad492f2bef6f82
Source referenceLinux
git.kernel.org/stable/c/35f2013f83ef16f9f0331c4c3a8e8d161580d574
Source referenceLinux
git.kernel.org/stable/c/494c57572d2d5bc2839553ed41aabe92ed0f587c
Source referenceLinux
View 2 more references
git.kernel.org/stable/c/776e20e4fdc23c23687b511ffdc80047878049d3
Source referenceLinux
git.kernel.org/stable/c/ba985ce08471c555af2a2fbe217c1bc2e72a6d8c
Source referenceLinux

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification · not supplied
Additional publishers · not supplied

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-98979

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Environment requirements

These conditions apply together as specified by the publisher. A matching product name alone does not establish exposure.

Linux · platform conditions

Any condition may hold

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 5.8

Before: 5.10.273

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 5.8

Before: 5.15.224

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 5.8

Before: 6.1.191

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 5.8

Before: 6.6.160

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 5.8

Before: 6.12.113

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 5.8

Before: 6.18.57

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 5.8

Before: 7.2.11

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 5.8

Before: 7.3

Applicability preview
[
  {
    "nodes": [
      {
        "operator": "OR",
        "negate": false,
        "cpeMatch": [
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "5.8",
            "versionEndExcluding": "5.10.273"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "5.8",
            "versionEndExcluding": "5.15.224"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "5.8",
            "versionEndExcluding": "6.1.191"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "5.8",
            "versionEndExcluding": "6.6.160"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "5.8",
            "versionEndExcluding": "6.12.113"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "5.8",
            "versionEndExcluding": "6.18.57"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "5.8",
            "versionEndExcluding": "7.2.11"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "5.8",
            "versionEndExcluding": "7.3"
          }
        ]
      }
    ]
  }
]
Contributing organizations · 1
Linux

Assigning organization

2026-10-30

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
No substantive changes have been recorded here yet. History starts when cve.new observes a change after tracking is enabled; earlier edits are not reconstructed.

Large field values are marked as truncated previews. Original source snapshots remain retained.