Shim: rce in http boot support may lead to secure boot bypass

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Summary

CVECVE-2023-40547
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2024-01-25 16:15:07 UTC
Updated2026-06-26 10:16:21 UTC
DescriptionA remote code execution vulnerability was found in Shim. The Shim boot support trusts attacker-controlled values when parsing an HTTP response. This flaw allows an attacker to craft a specific malicious HTTP request, leading to a completely controlled out-of-bounds write primitive and complete system compromise. This flaw is only exploitable during the early boot phase, an attacker needs to perform a Man-in-the-Middle or compromise the boot server to be able to exploit this vulnerability successfully.

Risk And Classification

Primary CVSS: v3.1 8.3 HIGH from [email protected]

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS: 0.048520000 probability, percentile 0.909200000 (date 2026-06-29)

Problem Types: CWE-787 | CWE-346 | CWE-787 Out-of-bounds Write

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary8.3HIGHCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
3.1[email protected]Secondary8.3HIGHCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
3.1CNACVSS8.3HIGHCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Redhat Enterprise Linux 7.0 All All All
Operating System Redhat Enterprise Linux 8.0 All All All
Operating System Redhat Enterprise Linux 9.0 All All All
Application Redhat Shim All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Enterprise Linux 7 unaffected 0:15.8-3.el7 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 7 unaffected 0:15.8-1.el7 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8 unaffected 0:15.8-4.el8_9 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.2 Advanced Update Support unaffected 0:15.8-2.el8_2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.2 Telecommunications Update Service unaffected 0:15.8-2.el8_2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.2 Update Services For SAP Solutions unaffected 0:15.8-2.el8_2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support unaffected 0:15.8-2.el8_4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Telecommunications Update Service unaffected 0:15.8-2.el8_4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Update Services For SAP Solutions unaffected 0:15.8-2.el8_4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support unaffected 0:15.8-2.el8_6 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Extended Update Support unaffected 0:15.8-2.el8 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Extended Update Support unaffected 0:15.8-2.el8 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9 unaffected 0:15.8-4.el9_3 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.0 Extended Update Support unaffected 0:15.8-3.el9 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.0 Extended Update Support unaffected 0:15.8-2.el9 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.0 Extended Update Support unaffected 0:15.8-2.el9 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.2 Extended Update Support unaffected 0:15.8-3.el9_2 * rpm Not specified

References

ReferenceSourceLinkTags
lists.debian.org/debian-lts-announce/2024/05/msg00009.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
access.redhat.com/errata/RHSA-2024:1883 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
access.redhat.com/errata/RHSA-2024:1902 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
access.redhat.com/errata/RHSA-2024:1873 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
access.redhat.com/errata/RHSA-2024:1834 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
cve-details af854a3a-2127-422b-91ae-364da2661108 access.redhat.com Vendor Advisory
access.redhat.com/errata/RHSA-2024:2086 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
2234589 – (CVE-2023-40547) CVE-2023-40547 shim: RCE in http boot support may lead to Secure Boot bypass af854a3a-2127-422b-91ae-364da2661108 bugzilla.redhat.com Issue Tracking, Vendor Advisory
access.redhat.com/errata/RHSA-2024:1835 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
oss-security - shim 15.8 released with 6 CVE fixes af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
access.redhat.com/errata/RHSA-2024:1903 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
access.redhat.com/errata/RHSA-2024:1876 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
access.redhat.com/errata/RHSA-2024:1959 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Red Hat would like to thank Bill Demirkapi (Microsoft Security Response Center) for reporting this issue. (en)

Additional Advisory Data

SourceTimeEvent
CNA2023-05-05T00:00:00.000ZReported to Red Hat.
CNA2024-01-23T00:00:00.000ZMade public.

Workarounds

CNA: If a system isn’t required to boot from the network, configure the server’s boot order to disable entirely or skip the network boot.

Legacy QID Mappings

  • 357274 Amazon Linux Security Advisory for shim : ALAS2-2024-2484
  • 379359 Shim package Multiple Vulnerabilities
  • 673479 EulerOS Security Update for shim (EulerOS-SA-2024-1249)
  • 673695 EulerOS Security Update for shim (EulerOS-SA-2024-1227)
  • 674149 EulerOS Security Update for shim (EulerOS-SA-2024-1497)
  • 674157 EulerOS Security Update for shim (EulerOS-SA-2024-1518)
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