CVE-2023-53621

Kernel crash via premature memory-cgroup ID publication

Published Oct 7, 2025 · Updated Oct 7, 2025

NULL pointer dereference in Linux kernel 6.3 through 6.5.3 allows local users to crash the kernel during memory-cgroup traversal. workingset_test_recent can resolve an evicted folio's reused memcg ID to a newly allocated memcg before hierarchy attachment, then pass it into mem_cgroup_get_nr_swap_pages for a NULL parent dereference. Triggering the rare race requires low-privileged local access and eviction-refault activity; the bounded consequence is a kernel oops and service interruption.

CVSS severity7.8
High
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Linux kernel 6.3 through 6.5.3 allows local users to crash the kernel during memory-cgroup traversal. workingset_test_recent can resolve an evicted folio's reused memcg ID to a newly allocated memcg before hierarchy attachment, then pass it into mem_cgroup_get_nr_swap_pages for a NULL parent dereference. Triggering the rare race requires low-privileged local access and eviction-refault activity; the bounded consequence is a kernel oops and service interruption.

The record

CVE
CVE-2023-53621
Published
Oct 7, 2025
Updated
Oct 7, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 7, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 7, 2025Record 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=6.3
  2. Affected versionversion=f78dfc7b77d5c3527d0f895bef693f711802de5a <6f0df8e16eb543167f2929cb756e695709a3551d
  3. Affected versionversion=f78dfc7b77d5c3527d0f895bef693f711802de5a <b9d30c38ee859d833a51131b5b4b864c7a6219d0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.3; version=f78dfc7b77d5c3527d0f895bef693f711802de5a <6f0df8e16eb543167f2929cb756e695709a3551d; version=f78dfc7b77d5c3527d0f895bef693f711802de5a <b9d30c38ee859d833a51131b5b4b864c7a6219d0

Published CVSS scores

7.8NIST NVDCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-476NULL Pointer Dereference
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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