CVE-2023-52504

Out-of-bounds read during early alternative patching

Published Mar 2, 2024 · Updated May 11, 2026

An out-of-bounds read in the Linux kernel affects KASAN-instrumented x86 systems using 5-level paging during early startup. While apply_alternatives() patches cpu_feature_enabled(X86_FEATURE_LA57), it rewrites values used to derive KASAN_SHADOW_START, causing KASAN instrumentation to read outside its expected shadow-memory bounds. Reachability requires 5-level paging and a KASAN-enabled kernel; published sources identify no attacker-controlled input or trigger.

CVSS severity7.1
High
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An out-of-bounds read in the Linux kernel affects KASAN-instrumented x86 systems using 5-level paging during early startup. While apply_alternatives() patches cpu_feature_enabled(X86_FEATURE_LA57), it rewrites values used to derive KASAN_SHADOW_START, causing KASAN instrumentation to read outside its expected shadow-memory bounds. Reachability requires 5-level paging and a KASAN-enabled kernel; published sources identify no attacker-controlled input or trigger.

The record

CVE
CVE-2023-52504
Published
Mar 2, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-125
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 2, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=4.17
  2. Affected versionversion=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <3719d3c36aa853d5a2401af9f8d6b116c91ad5ae
  3. Affected versionversion=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <3770c38cd6a60494da29ac2da73ff8156440a2d1
  4. Affected versionversion=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <5b784489c8158518bf7a466bb3cc045b0fb66b4b
  5. Affected versionversion=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <6788b10620ca6e98575d1e06e72a8974aad7657e
  6. Affected versionversion=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <cd287cc208dfe6bd6da98e7f88e723209242c9b4
  7. Affected versionversion=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <d35652a5fc9944784f6f50a5c979518ff8dacf61
  8. Affected versionversion=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <ecba5afe86f30605eb9dfb7f265a8de0218d4cfc

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.17; version=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <3719d3c36aa853d5a2401af9f8d6b116c91ad5ae; version=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <3770c38cd6a60494da29ac2da73ff8156440a2d1; version=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <5b784489c8158518bf7a466bb3cc045b0fb66b4b; version=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <6788b10620ca6e98575d1e06e72a8974aad7657e; version=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <cd287cc208dfe6bd6da98e7f88e723209242c9b4; version=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <d35652a5fc9944784f6f50a5c979518ff8dacf61; version=6657fca06e3ffab8d0b3f9d8b397f5ee498952d7 <ecba5afe86f30605eb9dfb7f265a8de0218d4cfc

Published CVSS scores

7.1NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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-125Out-of-bounds Read

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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