CVE-2026-31448Network attack vector

Filesystem hang via stale ext4 extent mapping

Published Apr 22, 2026 · Updated Apr 22, 2026

Infinite loop in ext4 in Linux Kernel allows remote attackers to hang filesystem operations through directory-creation requests. ext4_ext_map_blocks() frees a physical block after a failed extent insertion but leaves its mapping in the extent tree, allowing later mkdir or mknod activity to reuse the stale block as an xattr block. The trigger requires a post-insertion metadata error; the resulting buffer-head alias can trap ext4_xattr_block_set() in a loop while the inode lock remains held.

CVSS severity9.4
Critical
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite loop in ext4 in Linux Kernel allows remote attackers to hang filesystem operations through directory-creation requests. ext4_ext_map_blocks() frees a physical block after a failed extent insertion but leaves its mapping in the extent tree, allowing later mkdir or mknod activity to reuse the stale block as an xattr block. The trigger requires a post-insertion metadata error; the resulting buffer-head alias can trap ext4_xattr_block_set() in a loop while the inode lock remains held.

The record

CVE
CVE-2026-31448
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3a7667595bcad84da53fc156a418e110267c3412
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <416c86f30f91b4fb2642ef6b102596ca898f41a5
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5422fe71d26d42af6c454ca9527faaad4e677d6c
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <64f425b06b3bea9abc8977fd3982779b3ad070c9
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c66545e83a802c3851d9be27a41c0479dd29ff0c
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ecc50bfca9b5c2ee6aeef998181689b80477367b

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3a7667595bcad84da53fc156a418e110267c3412; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <416c86f30f91b4fb2642ef6b102596ca898f41a5; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5422fe71d26d42af6c454ca9527faaad4e677d6c; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <64f425b06b3bea9abc8977fd3982779b3ad070c9; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c66545e83a802c3851d9be27a41c0479dd29ff0c; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ecc50bfca9b5c2ee6aeef998181689b80477367b

Published CVSS scores

9.4kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Endpoint Denial of Service: Application 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

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Your stack

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