Summary
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.
Fixed packages 2
| Release | Package | Fixed in |
|---|---|---|
| AlmaLinux · 9 | shim-aa64 | 15.8-4.el9_3.alma.1 |
| AlmaLinux · 9 | shim-x64 | 15.8-4.el9_3.alma.1 |
Vulnerabilities 6
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High 8.3
Shim: rce in http boot support may lead to secure boot bypass
A remote code execution vulnerability was found in Shim. The Shim boot support trusts attacker-controlled values when parsing an HTTP response. This flaw allows an attacker to craft a specific malicious HTTP request, leading to a completely controlled out-of-…
-
High 7.4
Shim: interger overflow leads to heap buffer overflow in verify_sbat_section on 32-bits systems
A buffer overflow was found in Shim in the 32-bit system. The overflow happens due to an addition operation involving a user-controlled value parsed from the PE binary being used by Shim. This value is further used for memory allocation operations, leading to…
-
Medium 6.2
Shim: out-of-bounds read printing error messages
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 forma…
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Medium 6.2
Shim: out-of-bounds read in verify_buffer_authenticode() malformed pe file
An out-of-bounds read flaw was found in Shim due to the lack of proper boundary verification during the load of a PE binary. This flaw allows an attacker to load a crafted PE binary, triggering the issue and crashing Shim, resulting in a denial of service.
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Medium 5.5
Shim: out-of-bound read in verify_buffer_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.
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Medium 5.1
Shim: out of bounds read when parsing mz binaries
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.
References
-
report
https://access.redhat.com/security/cve/CVE-2023-40546
-
report
https://access.redhat.com/security/cve/CVE-2023-40547
-
report
https://access.redhat.com/security/cve/CVE-2023-40548
-
report
https://access.redhat.com/security/cve/CVE-2023-40549
-
report
https://access.redhat.com/security/cve/CVE-2023-40550
-
report
https://access.redhat.com/security/cve/CVE-2023-40551
-
report
https://bugzilla.redhat.com/2234589
-
report
https://bugzilla.redhat.com/2241782
-
report
https://bugzilla.redhat.com/2241796
-
report
https://bugzilla.redhat.com/2241797
-
report
https://bugzilla.redhat.com/2259915
-
report
https://bugzilla.redhat.com/2259918
-
advisory
https://errata.almalinux.org/9/ALSA-2024-1903.html