CVE-2026-74307

System deadlock via late donor superblock validation

Published Aug 15, 2026 · Updated Aug 15, 2026

Denial of service in the Linux kernel ext4 code since 3.18 allows local users to deadlock the system through EXT4_IOC_MOVE_EXT. EXT4_IOC_MOVE_EXT checks whether the donor file shares the original file's superblock only after lock_two_nondirectories() takes inode locks, permitting an overlayfs donor and concurrent filesystem freeze to form a circular wait. Exploitation requires local low-privileged access, files on different filesystems, and a concurrent freeze; the resulting impact is a system hang.

CVSS severity4.7
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

Denial of service in the Linux kernel ext4 code since 3.18 allows local users to deadlock the system through EXT4_IOC_MOVE_EXT. EXT4_IOC_MOVE_EXT checks whether the donor file shares the original file's superblock only after lock_two_nondirectories() takes inode locks, permitting an overlayfs donor and concurrent filesystem freeze to form a circular wait. Exploitation requires local low-privileged access, files on different filesystems, and a concurrent freeze; the resulting impact is a system hang.

The record

CVE
CVE-2026-74307
Published
Aug 15, 2026
Updated
Aug 15, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-617, T1499
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=3.18
  2. Affected versionversion=fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a <74796e886ca39fcb0d3fd36ea6a39c62784ab6fb
  3. Affected versionversion=fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a <c143957520c6c9b5cd72e0de8b52b814f0c576fe
  4. Affected versionversion=fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a <fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.18; version=fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a <74796e886ca39fcb0d3fd36ea6a39c62784ab6fb; version=fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a <c143957520c6c9b5cd72e0de8b52b814f0c576fe; version=fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a <fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c

Published CVSS scores

4.7Amazon LinuxCVSS:3.1/AV:L/AC:H/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-617Reachable Assertion
T1499Endpoint Denial of Service

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