Home/CVE/A buffer overflow was found in Shim in the 32-bit system. The overflow happens due to an addition operation involving a
CVE

CVE-2023-40548

A buffer overflow was found in Shim in the 32-bit system. The overflow happens due to an addition operation involving a

A buffer overflow was found in Shim in the 32-bit system. The overflow happens due to an addition operation involving a user-controlled value parsed from the PE binary being used by Shim. This value is further used for memory allocation operations, leading to a heap-based buffer overflow.

This flaw causes memory corruption and can lead to a crash or data integrity issues during the boot phase.

HIGH · CVSS 7.4 EPSS 0.00032
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules6 YARA rules0
⬡

Weakness Classification

CWE-190Integer Overflow or Wraparound
CWE-787Out-of-bounds Write
CWE-787Out-of-bounds Write
▤

Affected Products & Versions

3
redhat shim< 15.8
redhat shimall versions
fedoraproject fedoraall 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

7.4
HIGH · 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 · 03:15 PM
CVSS VectorCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
total
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-2023-40548
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-2023-40548Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2241782Issue TrackingVendor Advisory
https://lists.debian.org/debian-lts-announce/2024/05/msg00009.html
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