CVE-2023-40546

Shim: out-of-bounds read printing error messages

MEDIUM
5.5
CVSS Score
Published: January 29, 2024 at 04:29 PM UTC
Updated: June 17, 2026 at 06:18 AM UTC
3 products affected across 2 vendorsFedoraEnterprise LinuxShim

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Vendor states this is fixed in 0:15.8-1.el7 (unaffected)
Vendor states this is fixed in 0:15.8-2.el8 (unaffected)
Vendor states this is fixed in 0:15.8-2.el8_2 (unaffected)
Vendor states this is fixed in 0:15.8-2.el8_4 (unaffected)
Vendor states this is fixed in 0:15.8-2.el8_6 (unaffected)
Vendor states this is fixed in 0:15.8-2.el9 (unaffected)
Vendor states this is fixed in 0:15.8-3.el7 (unaffected)
Vendor states this is fixed in 0:15.8-3.el9 (unaffected)
Vendor states this is fixed in 0:15.8-3.el9_2 (unaffected)
Vendor states this is fixed in 0:15.8-4.el8_9 (unaffected)
Vendor states this is fixed in 0:15.8-4.el9_3 (unaffected)
v < 15.8
Affected range stops below 15.8, so it looks safe — our inference, not a vendor statement

References (12)

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-476

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