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NVD / CVE Program· CNA Linux

CVE-2026-74307: ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT

Noroxi assessment

Priority: Monitor (action score 0/100)

  • 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).
  • Fixed version: Linux Linux 23380fc1bf5d3b75dcbd51eb72be4eb0a3300370, 29e07ec352f0ad06c833a18bf47d82c81f55544f, 663f184b51492093d408e518efc95ee13b5b4440; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes.

Low priority for now. Upgrade to Linux Linux 23380fc1bf5d3b75dcbd51eb72be4eb0a3300370, 29e07ec352f0ad06c833a18bf47d82c81f55544f, 663f184b51492093d408e518efc95ee13b5b4440; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 Release Notes; 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: 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.

—No exploit Fix available
Published
Aug 15, 2026
Updated
Oct 30, 2026
EPSS
0.1% · 6th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

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—

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

    • 3.18affected
    • fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a and later · before 23380fc1bf5d3b75dcbd51eb72be4eb0a3300370affected · git
    • fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a and later · before 663f184b51492093d408e518efc95ee13b5b4440affected · git
    • fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a and later · before 74796e886ca39fcb0d3fd36ea6a39c62784ab6fbaffected · git
    • fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a and later · before 29e07ec352f0ad06c833a18bf47d82c81f55544faffected · git
    • fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a and later · before fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6caffected · git
    • fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a and later · before c143957520c6c9b5cd72e0de8b52b814f0c576feaffected · git
    • before 3.18not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

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-2026-74302Aug 15, 2026 · Bluetooth: hci_core: Fix UAF in hci_unregister_dev()
    31Monitor
  • ← EarlierCVE-2026-74305Aug 15, 2026 · bpf: Tighten cgroup storage cookie checks for prog arrays
    31Monitor
  • Later →CVE-2026-74308Aug 15, 2026 · ext4: fix kernel BUG in ext4_write_inline_data_end
    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 Linux23380fc1bf5d3b75dcbd51eb72be4eb0a3300370Vendor (CNA)
Linux Linux29e07ec352f0ad06c833a18bf47d82c81f55544fVendor (CNA)
Linux Linux663f184b51492093d408e518efc95ee13b5b4440Vendor (CNA)
Linux Linux74796e886ca39fcb0d3fd36ea6a39c62784ab6fbVendor (CNA)
Linux Linuxc143957520c6c9b5cd72e0de8b52b814f0c576feVendor (CNA)
Linux Linuxfb52013cad9e9b7d3a6a14ea1bcd841e41da7c6cVendor (CNA)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
debian:linux6.12.100-1 · Debian:13Package 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.

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

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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

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

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. Fix✗ → ✓

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References

Show all references (5 more)

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

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