Linux Kernel up to 6.12.96/7.1.4 ext4 ext4_move_extents deadlock

CVSS Meta Temp Score
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CTI Interest Score
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5.3$0-$5k0.94+

Summaryinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.12.96/7.1.4. Affected is the function ext4_move_extents of the component ext4. Performing a manipulation results in deadlock. This vulnerability is cataloged as CVE-2026-74307. The attack must be initiated from a local position. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.12.96/7.1.4. This affects the function ext4_move_extents of the component ext4. The manipulation with an unknown input leads to a deadlock vulnerability. CWE is classifying the issue as CWE-833. The product contains multiple threads or executable segments that are waiting for each other to release a necessary lock, resulting in deadlock. This is going to have an impact on availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT Reject the EXT4_IOC_MOVE_EXT ioctl early if the donor file does not belong to the same superblock as the original file. Currently, this validation is performed inside ext4_move_extents() by mext_check_validity(), but only after lock_two_nondirectories() has already acquired the inode locks. When the donor fd refers to a file on a different filesystem (e.g., overlayfs), this late validation creates a circular lock dependency: CPU0 (overlayfs write) CPU1 (ext4 ioctl) ---- ---- inode_lock(ovl_inode) mnt_want_write_file(filp) sb_start_write(ext4_sb) [sb_writers] backing_file_write_iter() vfs_iter_write(real_file) file_start_write(real_file) sb_start_write(ext4_sb) [blocked by freeze] lock_two_nondirectories() inode_lock(ovl_inode) [blocked] With a concurrent freeze operation holding sb_writers write side, this forms a deadlock cycle: CPU0 waits for freeze to complete, freeze waits for CPU1's sb_writers reader to exit, CPU1 waits for CPU0's inode lock. Since EXT4_IOC_MOVE_EXT exchanges physical extents between two files, it fundamentally requires both files to reside on the same ext4 filesystem. Moving the superblock check before any lock acquisition is both semantically correct and eliminates the circular dependency by ensuring that cross-filesystem donor fds are rejected before sb_writers or inode locks are taken.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-74307 since 08/15/2026. The exploitability is told to be easy. Attacking locally is a requirement. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 6.12.97, 7.1.5 or 7.2-rc1 eliminates this vulnerability. Applying the patch 74796e886ca39fcb0d3fd36ea6a39c62784ab6fb/fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c/c143957520c6c9b5cd72e0de8b52b814f0c576fe is able to eliminate this problem.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.3

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Deadlock
CWE: CWE-833 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.97/7.1.5/7.2-rc1
Patch: 74796e886ca39fcb0d3fd36ea6a39c62784ab6fb/fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c/c143957520c6c9b5cd72e0de8b52b814f0c576fe

Timelineinfo

08/15/2026 Advisory disclosed
08/15/2026 +0 days CVE reserved
08/15/2026 +0 days VulDB entry created
08/15/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-74307 (🔒)
GCVE (CVE): GCVE-0-2026-74307
GCVE (VulDB): GCVE-100-390279

Entryinfo

Created: 08/15/2026 09:22
Changes: 08/15/2026 09:22 (59)
Complete: 🔍
Cache ID: 216::103

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