CVE-2026-72315

Unmount denial of service via delayed dentry release

Published Aug 15, 2026 · Updated Aug 15, 2026

Improper reference-count handling in Linux kernel SMB clients allows local users to prevent a CIFS file system from unmounting. The direct-I/O cleanup path queues netfs_free_request after the write returns, delaying the final cfile put and dentry release beyond cifs_kill_sb. Triggering unmount before deferred cleanup reaches the workqueues leaves a busy dentry, emits a kernel warning, and blocks the unmount.

CVSS severity5.5
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper reference-count handling in Linux kernel SMB clients allows local users to prevent a CIFS file system from unmounting. The direct-I/O cleanup path queues netfs_free_request after the write returns, delaying the final cfile put and dentry release beyond cifs_kill_sb. Triggering unmount before deferred cleanup reaches the workqueues leaves a busy dentry, emits a kernel warning, and blocks the unmount.

The record

CVE
CVE-2026-72315
Published
Aug 15, 2026
Updated
Aug 15, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-911, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0629a1a187e424373364d681b42b101894bdb548
  2. Affected versionversion=0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd
  3. Affected versionversion=30afc6ea72cc6cf7c8d579e79b64232801c38d08
  4. Affected versionversion=340cea84f691c5206561bb2e0147158fe02070be <75f5c412fa867efa0bf9b646bffe0d912109e84a
  5. Affected versionversion=340cea84f691c5206561bb2e0147158fe02070be <f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214
  6. Affected versionversion=6.1.167 <6.2
  7. Affected versionversion=6.12.78 <6.13
  8. Affected versionversion=6.18.20 <6.19
  9. Affected versionversion=6.19.10 <6.20
  10. Affected versionversion=6.6.130 <6.7
  11. Affected versionversion=7.0
  12. Affected versionversion=708c276f516d27beaded7f372ac8111cee43926c
  13. Affected versionversion=f655467a9973f964b267871e5fef533ad5014494

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0629a1a187e424373364d681b42b101894bdb548; version=0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd; version=30afc6ea72cc6cf7c8d579e79b64232801c38d08; version=340cea84f691c5206561bb2e0147158fe02070be <75f5c412fa867efa0bf9b646bffe0d912109e84a; version=340cea84f691c5206561bb2e0147158fe02070be <f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214; version=6.1.167 <6.2; version=6.12.78 <6.13; version=6.18.20 <6.19; version=6.19.10 <6.20; version=6.6.130 <6.7; version=7.0; version=708c276f516d27beaded7f372ac8111cee43926c; version=f655467a9973f964b267871e5fef533ad5014494

Published CVSS scores

2.5Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
5.5Red HatCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-911Improper Update of Reference Count
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo