The following advisory data is extracted from:
https://access.redhat.com/security/data/csaf/v2/advisories/2024/rhsa-2024_1883.json
Red Hat officially shut down their mailing list notifications October 10, 2023.  Due to this, Packet Storm has recreated the below data as a reference point to raise awareness.  It must be noted that due to an inability to easily track revision updates without crawling Red Hat's archive, these advisories are single notifications and we strongly suggest that you visit the Red Hat provided links to ensure you have the latest information available if the subject matter listed pertains to your environment.
- Packet Storm Staff
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Red Hat Security Advisory
Synopsis:           Important: shim security update
Advisory ID:        RHSA-2024:1883-03
Product:            Red Hat Enterprise Linux
Advisory URL:       https://access.redhat.com/errata/RHSA-2024:1883
Issue date:         2024-04-18
Revision:           03
CVE Names:          CVE-2023-40546
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Summary: 
An update for shim is now available for Red Hat Enterprise Linux 8.8 Extended
Update Support.
Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.
Description:
The shim package contains a first-stage UEFI boot loader that handles chaining
to a trusted full boot loader under secure boot environments.
Security Fix(es):
* shim: RCE in http boot support may lead to Secure Boot bypass (CVE-2023-40547)
* shim: Interger overflow leads to heap buffer overflow in verify_sbat_section
on 32-bits systems (CVE-2023-40548)
* shim: Out-of-bounds read printing error messages (CVE-2023-40546)
* shim: Out-of-bounds read in verify_buffer_authenticode() malformed PE file
(CVE-2023-40549)
* shim: Out-of-bound read in verify_buffer_sbat() (CVE-2023-40550)
* shim: out of bounds read when parsing MZ binaries (CVE-2023-40551)
For more details about the security issue(s), including the impact, a CVSS
score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
Solution:
https://access.redhat.com/articles/11258
CVEs:
CVE-2023-40546
References:
https://access.redhat.com/security/updates/classification/#important
https://bugzilla.redhat.com/show_bug.cgi?id=2234589
https://bugzilla.redhat.com/show_bug.cgi?id=2241782
https://bugzilla.redhat.com/show_bug.cgi?id=2241796
https://bugzilla.redhat.com/show_bug.cgi?id=2241797
https://bugzilla.redhat.com/show_bug.cgi?id=2259915
https://bugzilla.redhat.com/show_bug.cgi?id=2259918