CVE-2023-40551

Shim: out of bounds read when parsing mz binaries

MEDIUM

5.1

CVSS Score

Published: January 29, 2024 at 04:46 PM UTC

Updated: June 17, 2026 at 06:18 AM UTC

3 products affected across 2 vendorsFedoraEnterprise LinuxShim

Using Red Hat Enterprise Linux 7 by Red Hat?

Get instant alerts when new vulnerabilities affect Red Hat Enterprise Linux 7 - before attackers find them.

Real-time alertsTrack your software stackFree plan available

Start Free Sign In

Severity

MEDIUM5.1

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

Description

A flaw was found in the MZ binary format in Shim. An out-of-bounds read may occur, leading to a crash or possible exposure of sensitive data during the system's boot phase.

Affected

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

Fedora · Fedora Projectrpm

95%

Enterprise Linux · Red Hatrpm

95%

8.0 9.0

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)

Shim · Red Hat

95%

v < 15.8

Affected range stops below 15.8, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references