Security readout for executives and security teams
Plain-English summary
CVE-2023-40546 is a Shim bootloader flaw that can crash the system during a specific error-handling path. The business impact is availability, not data theft or privilege escalation based on the supplied sources. It matters most for Red Hat systems using affected shim packages in Secure Boot environments.
Executive priority
Treat this as scheduled security maintenance for affected Linux boot infrastructure. It is not sourced as actively exploited, but a boot-time crash can still create operational disruption on important servers or workstations.
Technical view
When Shim fails while creating a new ESL variable, its error logging uses parameters that do not match the format string. The supplied record describes a crash under certain circumstances, mapped to CVSS 6.2 with local attack vector and high availability impact only.
Likely exposure
Exposure is likely limited to systems running the listed Red Hat Enterprise Linux 7, 8, 8.x lifecycle streams, 9, and 9.x EUS shim-related packages at affected versions.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The CVSS vector is local, requires no privileges or user interaction, and impacts availability rather than confidentiality or integrity.
Researcher notes
Evidence is strongest for Red Hat package impact and advisory availability. The supplied data describes the bug as an error-path logging mismatch causing a crash; it does not provide exploit details, broad vendor impact, or independent exploitation confirmation.
Mitigation direction
- Apply the relevant Red Hat shim updates from the listed RHSA advisories.
- Prioritize Secure Boot systems and RHEL lifecycle streams named as affected.
- Check Red Hat guidance for any stream-specific installation or bootloader handling.
- Plan maintenance windows where boot component updates require validation.
Validation and detection
- Inventory installed shim, shim-signed, and shim-unsigned package versions.
- Compare installed versions against the affected Red Hat package entries.
- Confirm the applicable RHSA advisory has been applied for each RHEL stream.
- Validate systems still boot successfully after remediation.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-476: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2023-40546 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.2 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H2.53.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.2MediumVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- RHSA-2024:1834CVE reference · vendor-advisory, x_refsource_REDHAT
- RHSA-2024:1835CVE reference · vendor-advisory, x_refsource_REDHAT
- RHSA-2024:1873CVE reference · vendor-advisory, x_refsource_REDHAT
- RHSA-2024:1876CVE reference · vendor-advisory, x_refsource_REDHAT
- RHSA-2024:1883CVE reference · vendor-advisory, x_refsource_REDHAT
- RHSA-2024:1902CVE reference · vendor-advisory, x_refsource_REDHAT
- RHSA-2024:1903CVE reference · vendor-advisory, x_refsource_REDHAT
- RHSA-2024:1959CVE reference · vendor-advisory, x_refsource_REDHAT
- RHSA-2024:2086CVE reference · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2023-40546CVE reference · vdb-entry, x_refsource_REDHAT
- RHBZ#2241796CVE reference · issue-tracking, x_refsource_REDHAT
- https://lists.debian.org/debian-lts-announce/2024/05/msg00009.htmlCVE reference · x_transferred
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
NULL Pointer Dereference
NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.