CVE-2023-5342

Boot integrity bypass via expired signing certificate

Published Aug 15, 2025 · Updated Aug 15, 2025

Expired-key validation in Fedora Project shim-x64 15.6-2 allows local users to load old or invalid signed boot components. The embedded Fedora Secure Boot CA expired in December 2022, but the trust path continued accepting components signed under that certificate. Exploitation requires administrative control of boot components and affects boot-chain integrity without reported confidentiality or availability impact.

CVSS severity4.1
Medium
EPSS probability0.08%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Expired-key validation in Fedora Project shim-x64 15.6-2 allows local users to load old or invalid signed boot components. The embedded Fedora Secure Boot CA expired in December 2022, but the trust path continued accepting components signed under that certificate. Exploitation requires administrative control of boot components and affects boot-chain integrity without reported confidentiality or availability impact.

The record

CVE
CVE-2023-5342
Published
Aug 15, 2025
Updated
Aug 15, 2025
Vendor
Fedora Project
Product
shim-x64
Classifications
CWE-324, T1542.003
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Aug 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 15, 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=15.6-2 <15.8-2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Fedora Project · shim-x64version=15.6-2 <15.8-2

Published CVSS scores

4.1Fedora ProjectCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-324Use of a Key Past its Expiration Date
T1542.003Pre-OS Boot: Bootkit

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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