Home/CVE/An out-of-bounds read flaw was found in Shim when it tried to validate the SBAT information. This issue may expose sensi
CVE

CVE-2023-40550

An out-of-bounds read flaw was found in Shim when it tried to validate the SBAT information. This issue may expose sensi

An out-of-bounds read flaw was found in Shim when it tried to validate the SBAT information. This issue may expose sensitive data during the system's boot phase.

MEDIUM · CVSS 5.5 EPSS 0.00024
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules6 YARA rules0
⬡

Weakness Classification

CWE-125Out-of-bounds Read
CWE-125Out-of-bounds Read
▤

Affected Products & Versions

3
redhat shim< 15.8
fedoraproject fedoraall versions
redhat enterprise linuxall versions
◈

Sigma Hunt Rules

6
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighSuspicious Shim Database Patching Activity
producthighPotential Persistence Via Shim Database In Uncommon Location
productmediumNew Custom Shim Database Created
productmediumPotential Shim Database Persistence via Sdbinst.EXE
productmediumUncommon Extension Shim Database Installation Via Sdbinst.EXE
productmediumPotential Persistence Via Shim Database Modification
▣

Scoring & Timeline

5.5
MEDIUM · CVSS v3.1 · secalert@redhat.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD29 Jan 2024 · 05:15 PM
CVSS VectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

14
suse-csafSUSE-SU-2025:20136-1
msrcCVE-2023-40550
suse-csafSUSE-SU-2024:1461-1
suse-csafSUSE-SU-2024:1462-1
suse-csafSUSE-SU-2024:1368-1
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://access.redhat.com/security/cve/CVE-2023-40550Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2259915Issue TrackingVendor Advisory
https://lists.debian.org/debian-lts-announce/2024/05/msg00009.html
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