CVE-2026-23238

Local system crash via unchecked block-size failure

Published Mar 4, 2026 · Updated Mar 4, 2026

Reachable assertion in the Linux Kernel allows local users to crash the system by mounting ROMFS on a loop device with an oversized block size. romfs_fill_super() ignores a zero return from sb_set_blocksize(), leaving the superblock at 32768 bytes before sb_bread() reaches the size assertion in folio_set_bh(). Triggering the crash requires permission to change a loop device's block size and mount it; the result is a kernel BUG and system service interruption.

CVSS severity5.5
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in the Linux Kernel allows local users to crash the system by mounting ROMFS on a loop device with an oversized block size. romfs_fill_super() ignores a zero return from sb_set_blocksize(), leaving the superblock at 32768 bytes before sb_bread() reaches the size assertion in folio_set_bh(). Triggering the crash requires permission to change a loop device's block size and mount it; the result is a kernel BUG and system service interruption.

The record

CVE
CVE-2026-23238
Published
Mar 4, 2026
Updated
Mar 4, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-617, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 4, 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 <2c5829cd8fbbc91568c520b666898f57cdcb8cf6
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4b71ad7676564a94ec5f7d18298f51e8ae53db73
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9b203b8ddd7359270e8a694d0584743555128e2c
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a381f0f61b35c8894b0bd0d6acef2d8f9b08b244
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ab7ad7abb3660c58ffffdf07ff3bb976e7e0afa0
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <cbd9931e6456822067725354d83446c5bb813030
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f2521ab1f63a8c244f06a080319e5ff9a2e1bd95

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2c5829cd8fbbc91568c520b666898f57cdcb8cf6; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4b71ad7676564a94ec5f7d18298f51e8ae53db73; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9b203b8ddd7359270e8a694d0584743555128e2c; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a381f0f61b35c8894b0bd0d6acef2d8f9b08b244; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ab7ad7abb3660c58ffffdf07ff3bb976e7e0afa0; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <cbd9931e6456822067725354d83446c5bb813030; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f2521ab1f63a8c244f06a080319e5ff9a2e1bd95

Published CVSS scores

5.5NIST NVDCVSS: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.

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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
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

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Your stack

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