How severe is CVE-2023-40548?

CVE-2023-40548 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over local access with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-40548 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-40548?

CVE-2023-40548 primarily affects Redhat Shim. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-40548?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2023-40548 have an EU (EUVD) identifier?

Yes. CVE-2023-40548 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-45119.

When was CVE-2023-40548 published?

CVE-2023-40548 was published on 2024-01-29 and last updated on 2026-06-26.

CVE-2023-40548

CVE-2023-40548 is a high-severity vulnerability in Redhat Shim with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-190.

Key facts

Severity: High (CVSS 3.x base score 7.4)
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2023-45119
Weakness: CWE-190
Affected product: Redhat Shim
Published: 2024-01-29
Last modified: 2026-06-26

Description

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.

Frequently asked questions

What is 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 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.
How severe is CVE-2023-40548?: CVE-2023-40548 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over local access with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2023-40548 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-40548?: CVE-2023-40548 primarily affects Redhat Shim. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-40548?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2023-40548 have an EU (EUVD) identifier?: Yes. CVE-2023-40548 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-45119.
When was CVE-2023-40548 published?: CVE-2023-40548 was published on 2024-01-29 and last updated on 2026-06-26.

References

Affected products (3)

cpe:2.3:a:redhat:shim:*:*:*:*:*:*:*:*
cpe:2.3:a:redhat:shim:15.8:rc1:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*

More vulnerabilities in Redhat Shim

CVE-2023-40547 — High (CVSS 8.3): A remote code execution vulnerability was found in Shim. The Shim boot support trusts attacker-controlled values when…
CVE-2014-3677 — High (CVSS 7.5): Unspecified vulnerability in Shim might allow attackers to execute arbitrary code via a crafted MOK list, which…
CVE-2014-3676 — High (CVSS 7.5): Heap-based buffer overflow in Shim allows remote attackers to execute arbitrary code via a crafted IPv6 address,…
CVE-2022-28737 — Medium (CVSS 6.5): There's a possible overflow in handle_image() when shim tries to load and execute crafted EFI executables; The…
CVE-2023-40549 — Medium (CVSS 6.2): An out-of-bounds read flaw was found in Shim due to the lack of proper boundary verification during the load of a PE…
CVE-2023-40546 — Medium (CVSS 6.2): A flaw was found in Shim when an error happened while creating a new ESL variable. If Shim fails to create the new…

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