How severe is CVE-2023-40546?

CVE-2023-40546 has a CVSS 3.x base score of 6.2, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2023-40546 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-2023-40546?

CVE-2023-40546 primarily affects Redhat Shim. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-40546?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2023-40546 have an EU (EUVD) identifier?

Yes. CVE-2023-40546 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-45117.

When was CVE-2023-40546 published?

CVE-2023-40546 was published on 2024-01-29 and last updated on 2026-06-17.

CVE-2023-40546

CVE-2023-40546 is a medium-severity vulnerability in Redhat Shim with a CVSS 3.x base score of 6.2. 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-476.

Key facts

Severity: Medium (CVSS 3.x base score 6.2)
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2023-45117
Weakness: CWE-476
Affected product: Redhat Shim
Published: 2024-01-29
Last modified: 2026-06-17

Description

A flaw was found in Shim when an error happened while creating a new ESL variable. If Shim fails to create the new variable, it tries to print an error message to the user; however, the number of parameters used by the logging function doesn't match the format string used by it, leading to a crash under certain circumstances.

Frequently asked questions

What is CVE-2023-40546?: A flaw was found in Shim when an error happened while creating a new ESL variable. If Shim fails to create the new variable, it tries to print an error message to the user; however, the number of parameters used by the logging function doesn't match the format string used by it, leading to a crash under certain circumstances.
How severe is CVE-2023-40546?: CVE-2023-40546 has a CVSS 3.x base score of 6.2, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2023-40546 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-2023-40546?: CVE-2023-40546 primarily affects Redhat Shim. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-40546?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2023-40546 have an EU (EUVD) identifier?: Yes. CVE-2023-40546 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-45117.
When was CVE-2023-40546 published?: CVE-2023-40546 was published on 2024-01-29 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:redhat:shim:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*

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-2023-40548 — High (CVSS 7.4): A buffer overflow was found in Shim in the 32-bit system. The overflow happens due to an addition operation involving a…
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…

All CVEs affecting Redhat Shim →

Other CWE-476 (NULL Pointer Dereference) vulnerabilities

CVE-2022-36648 — Critical (CVSS 10.0): The hardware emulation in the of_dpa_cmd_add_l2_flood of rocker device model in QEMU, as used in 7.0.0 and earlier,…
CVE-2020-14500 — Critical (CVSS 10.0): Secomea GateManager all versions prior to 9.2c, An attacker can send a negative value and overwrite arbitrary data.
CVE-2010-2495 — Critical (CVSS 10.0): The pppol2tp_xmit function in drivers/net/pppol2tp.c in the L2TP implementation in the Linux kernel before 2.6.34 does…
CVE-2026-46195 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: validate dacloffset before building…
CVE-2026-31657 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: batman-adv: hold claim backbone gateways by…
CVE-2026-31436 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: dmaengine: idxd: fix possible wrong descriptor…

Browse all CWE-476 (NULL Pointer Dereference) vulnerabilities →