SARA / Free Tools / CVE / CVE-2023-40550

CVE-2023-40550 — An out-of-bounds read flaw was found in Shim when it tried to validate the SBAT

An out-of-bounds read flaw was found in Shim when it tried to validate the SBAT information. This issue may expose sensitive data during the system's boot phase.

CVSS

5.5 MEDIUM

EPSS

2.00% (top 93.80%)

CWE

CWE-125

Published

2024-01-29T16:29:23.050Z

Last modified

2026-01-27T10:55:03.902Z

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

01What is this vulnerability?

An out-of-bounds read flaw was found in Shim when it tried to validate the SBAT information. This issue may expose sensitive data during the system's boot phase.

02Affected products

Vendor	Product	Versions
Red Hat	Red Hat Enterprise Linux 7	0:15.8-3.el7
Red Hat	Red Hat Enterprise Linux 7	0:15.8-1.el7
Red Hat	Red Hat Enterprise Linux 8	0:15.8-4.el8_9
Red Hat	Red Hat Enterprise Linux 8.2 Advanced Update Support	0:15.8-2.el8_2
Red Hat	Red Hat Enterprise Linux 8.2 Telecommunications Update Service	0:15.8-2.el8_2
Red Hat	Red Hat Enterprise Linux 8.2 Update Services for SAP Solutions	0:15.8-2.el8_2
Red Hat	Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support	0:15.8-2.el8_4
Red Hat	Red Hat Enterprise Linux 8.4 Telecommunications Update Service	0:15.8-2.el8_4
Red Hat	Red Hat Enterprise Linux 8.4 Update Services for SAP Solutions	0:15.8-2.el8_4
Red Hat	Red Hat Enterprise Linux 8.6 Extended Update Support	0:15.8-2.el8_6
Red Hat	Red Hat Enterprise Linux 8.8 Extended Update Support	0:15.8-2.el8
Red Hat	Red Hat Enterprise Linux 8.8 Extended Update Support	0:15.8-2.el8
Red Hat	Red Hat Enterprise Linux 9	0:15.8-4.el9_3
Red Hat	Red Hat Enterprise Linux 9.0 Extended Update Support	0:15.8-3.el9
Red Hat	Red Hat Enterprise Linux 9.0 Extended Update Support	0:15.8-2.el9
Red Hat	Red Hat Enterprise Linux 9.0 Extended Update Support	0:15.8-2.el9
Red Hat	Red Hat Enterprise Linux 9.2 Extended Update Support	0:15.8-3.el9_2

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

Patch to a fixed version listed in the vendor advisory (see references below).
Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:

Open in Sigma generator →

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

Published: 2024-01-29T16:29:23.050Z
Last modified: 2026-01-27T10:55:03.902Z

09References

access.redhat.com — https://access.redhat.com/errata/RHSA-2024:1834
access.redhat.com — https://access.redhat.com/errata/RHSA-2024:1835
access.redhat.com — https://access.redhat.com/errata/RHSA-2024:1873
access.redhat.com — https://access.redhat.com/errata/RHSA-2024:1876
access.redhat.com — https://access.redhat.com/errata/RHSA-2024:1883
access.redhat.com — https://access.redhat.com/errata/RHSA-2024:1902
access.redhat.com — https://access.redhat.com/errata/RHSA-2024:1903
access.redhat.com — https://access.redhat.com/errata/RHSA-2024:1959
access.redhat.com — https://access.redhat.com/errata/RHSA-2024:2086
access.redhat.com — https://access.redhat.com/security/cve/CVE-2023-40550
bugzilla.redhat.com — https://bugzilla.redhat.com/show_bug.cgi?id=2259915

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