CVE-2023-53531

Local kernel crash via poll-timeout race

Published Oct 1, 2025 · Updated Aug 5, 2026

Race condition in the null_blk driver in the Linux kernel allows local users to crash the kernel via polled I/O to /dev/nullb0. null_poll() processes requests outside poll_lock while null_timeout_rq() can concurrently delete the same queue node after its next pointer is cleared. Access to the null_blk device and polled direct I/O are required; a successful collision dereferences NULL in kblockd and panics or wedges the kernel.

CVSS severity7.8
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in the null_blk driver in the Linux kernel allows local users to crash the kernel via polled I/O to /dev/nullb0. null_poll() processes requests outside poll_lock while null_timeout_rq() can concurrently delete the same queue node after its next pointer is cleared. Access to the null_blk device and polled direct I/O are required; a successful collision dereferences NULL in kblockd and panics or wedges the kernel.

The record

CVE
CVE-2023-53531
Published
Oct 1, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 1, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=0a593fbbc245a85940ed34caa3aa1e4cb060c54b <5a26e45edb4690d58406178b5a9ea4c6dcf2c105
  2. Affected versionversion=0a593fbbc245a85940ed34caa3aa1e4cb060c54b <a0b4a0666beacfe8add9c71d8922475541dbae73
  3. Affected versionversion=0a593fbbc245a85940ed34caa3aa1e4cb060c54b <a7cb2e709f2927cc3c76781df3e45de2381b3b9d
  4. Affected versionversion=5.16

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0a593fbbc245a85940ed34caa3aa1e4cb060c54b <5a26e45edb4690d58406178b5a9ea4c6dcf2c105; version=0a593fbbc245a85940ed34caa3aa1e4cb060c54b <a0b4a0666beacfe8add9c71d8922475541dbae73; version=0a593fbbc245a85940ed34caa3aa1e4cb060c54b <a7cb2e709f2927cc3c76781df3e45de2381b3b9d; version=5.16

Published CVSS scores

7.8Linux Kernel CVE TeamCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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 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

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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