Skip to content
Noroxi
CVE.org (no NVD analysis yet)· CNA Linux

CVE-2026-98978: namespace: never expire a locked mount

Noroxi assessment

Priority: Monitor (action score 33/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 6b8dc3713a76346d212abab46cbfc8d7070f534c, d23265a12e4991ce7aedce670c0b6b598cadb644, f78ddcc872248c7aa1d7e904928441a0be4c6d5d; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 6b8dc3713a76346d212abab46cbfc8d7070f534c, d23265a12e4991ce7aedce670c0b6b598cadb644, f78ddcc872248c7aa1d7e904928441a0be4c6d5d; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: namespace: never expire a locked mount Locked mounts are special. They protect the underlying files and directories from being revealed. do_umount() refuses to unmount locked mounts but shrink_submounts() doesn't. A shrinkable mount can become locked once the owner of a user namespace puts it beneath a locked mount with MOVE_MOUNT_BENEATH. The locked property now moves to the mount at the bottom making it possible to unmount the top mount. So umount() of an unlocked ancestor now expires the bottom mount first and the covered directory is revealed: move_mount(c -> x/hidden, MOVE_MOUNT_BENEATH) = 0 the cover after the lock moved: umount2(x/hidden) = 0 the holder of the lock: umount2(x/hidden) = EINVAL the root of the copy, busy: umount2(x) = EBUSY reads x/hidden/secret: "covered-by-root" So leave a locked mount alone as it dies together with its parent. A plain umount() of an unlocked mount with a locked one below it is EBUSY from now on. It's the same for any other locked child. A lazy umount still takes the whole tree. mark_mounts_for_expiry() never sees a locked mount. lock_mnt_tree() leaves a mount on an expiry list alone and nothing else puts a locked one on such a list. Add an assert for this.

HighCVSS 8.4 · v3.1—No exploit Fix available
Published
Oct 23, 2026
Updated
Oct 24, 2026
EPSS
0.1% · 6th percentile
CWE
—

Report tools

JSON

Action score

33

Monitor

Low priority for now.

CVSS
33 / 40 · 8.4 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
—
CNA · Linux
8.4
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-98978

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for linux records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 3.12affected
    • 5ff9d8a65ce80efb509ce4e8051394e9ed2cd942 and later · before 6b8dc3713a76346d212abab46cbfc8d7070f534caffected · git
    • 5ff9d8a65ce80efb509ce4e8051394e9ed2cd942 and later · before d23265a12e4991ce7aedce670c0b6b598cadb644affected · git
    • 5ff9d8a65ce80efb509ce4e8051394e9ed2cd942 and later · before f78ddcc872248c7aa1d7e904928441a0be4c6d5daffected · git
    • before 3.12not affected · semver
    • 6.18.57 and later · up to and including 6.18.*not affected · semver
    • 7.2.11 and later · up to and including 7.2.*not affected · semver
    • 7.3 and laternot affected · original_commit_for_fix

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:14linuxbefore 7.2.11-17.2.11-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-98976Oct 23, 2026 · namespace: keep the lock on a mount that a propagated copy is moved beneath
    31Monitor
  • ← EarlierCVE-2026-98977Oct 23, 2026 · namespace: handle mount locking for automounts correctly
    0Monitor
  • Later →CVE-2026-98979Oct 23, 2026 · namespace: refuse an automount below a mount that is in no namespace
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux6b8dc3713a76346d212abab46cbfc8d7070f534cVendor (CNA)
Linux Linuxd23265a12e4991ce7aedce670c0b6b598cadb644Vendor (CNA)
Linux Linuxf78ddcc872248c7aa1d7e904928441a0be4c6d5dVendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
debian:linux7.2.11-1 · Debian:14Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. Fix recordedsame day
  3. TodayOct 31, 2026+8 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
none

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
None

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. CVSS— → 8.4
  2. Severity— → high
  3. Exploit maturity— → none
  4. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records