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NVD / CVE Program· CNA Linux

CVE-2025-40105: vfs: Don't leak disconnected dentries on umount

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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: 0.16% (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 20863bb7fbb016379f8227122edfabc5c799bc79, 56094ad3eaa21e6621396cc33811d8f72847a834, 620f3b0ede9c5cb4976cd0457d0b04ad551e5d6b; azl3 kernel 6.6.112.1-2 on Azure Linux 3.0 6.6.117.1-1.

Low priority for now. Upgrade to Linux Linux 20863bb7fbb016379f8227122edfabc5c799bc79, 56094ad3eaa21e6621396cc33811d8f72847a834, 620f3b0ede9c5cb4976cd0457d0b04ad551e5d6b; azl3 kernel 6.6.112.1-2 on Azure Linux 3.0 6.6.117.1-1 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: vfs: Don't leak disconnected dentries on umount When user calls open_by_handle_at() on some inode that is not cached, we will create disconnected dentry for it. If such dentry is a directory, exportfs_decode_fh_raw() will then try to connect this dentry to the dentry tree through reconnect_path(). It may happen for various reasons (such as corrupted fs or race with rename) that the call to lookup_one_unlocked() in reconnect_one() will fail to find the dentry we are trying to reconnect and instead create a new dentry under the parent. Now this dentry will not be marked as disconnected although the parent still may well be disconnected (at least in case this inconsistency happened because the fs is corrupted and .. doesn't point to the real parent directory). This creates inconsistency in disconnected flags but AFAICS it was mostly harmless. At least until commit f1ee616214cb ("VFS: don't keep disconnected dentries on d_anon") which removed adding of most disconnected dentries to sb->s_anon list. Thus after this commit cleanup of disconnected dentries implicitely relies on the fact that dput() will immediately reclaim such dentries. However when some leaf dentry isn't marked as disconnected, as in the scenario described above, the reclaim doesn't happen and the dentries are "leaked". Memory reclaim can eventually reclaim them but otherwise they stay in memory and if umount comes first, we hit infamous "Busy inodes after unmount" bug. Make sure all dentries created under a disconnected parent are marked as disconnected as well.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Oct 30, 2025
Updated
Oct 19, 2026
EPSS
0.1% · 5th percentile
CWE
—

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
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.

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

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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.

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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

    • 4.16affected
    • f1ee616214cb22410e939d963bbb2349c2570f02 and later · before b5abafd0aa8d7bcb935c8f91e4cfc2f2820759e4affected · git
    • f1ee616214cb22410e939d963bbb2349c2570f02 and later · before 20863bb7fbb016379f8227122edfabc5c799bc79affected · git
    • f1ee616214cb22410e939d963bbb2349c2570f02 and later · before 8004d4b8cbf1bd68a23c160d57287e177c82cc69affected · git
    • f1ee616214cb22410e939d963bbb2349c2570f02 and later · before 7e0c8aaf4e28918abded547a5147c7d52c4af7d2affected · git
    • f1ee616214cb22410e939d963bbb2349c2570f02 and later · before cebfbf40056a4d858b2a3ca59a69936d599bd209affected · git
    • f1ee616214cb22410e939d963bbb2349c2570f02 and later · before 620f3b0ede9c5cb4976cd0457d0b04ad551e5d6baffected · git
    • f1ee616214cb22410e939d963bbb2349c2570f02 and later · before eadc49999fa994d6fbd70c332bd5d5051cc42261affected · git
    • f1ee616214cb22410e939d963bbb2349c2570f02 and later · before 56094ad3eaa21e6621396cc33811d8f72847a834affected · git
    • before 4.16not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.158-16.1.158-1
Debian:13linuxbefore 6.12.57-16.12.57-1
Debian:14linuxbefore 6.17.6-16.17.6-1

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-2025-40103Oct 30, 2025 · smb: client: Fix refcount leak for cifs_sb_tlink
    0Monitor
  • ← EarlierCVE-2025-40104Oct 30, 2025 · ixgbevf: fix mailbox API compatibility by negotiating supported features
    31Monitor
  • Later →CVE-2025-40106Oct 31, 2025 · comedi: fix divide-by-zero in comedi_buf_munge()
    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 Linux20863bb7fbb016379f8227122edfabc5c799bc79Vendor (CNA)
Linux Linux56094ad3eaa21e6621396cc33811d8f72847a834Vendor (CNA)
Linux Linux620f3b0ede9c5cb4976cd0457d0b04ad551e5d6bVendor (CNA)
Linux Linux7e0c8aaf4e28918abded547a5147c7d52c4af7d2Vendor (CNA)
Linux Linux8004d4b8cbf1bd68a23c160d57287e177c82cc69Vendor (CNA)
Linux Linuxb5abafd0aa8d7bcb935c8f91e4cfc2f2820759e4Vendor (CNA)
Linux Linuxcebfbf40056a4d858b2a3ca59a69936d599bd209Vendor (CNA)
Linux Linuxeadc49999fa994d6fbd70c332bd5d5051cc42261Vendor (CNA)
azl3 kernel 6.6.112.1-2 on Azure Linux 3.06.6.117.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.158-1 · Debian:12Package 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.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

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).

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
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

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. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (9 more)

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

All records