Shim OOBR read leaks sensitive data during boot
CVE-2023-40550 Published on January 29, 2024

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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Vulnerability Analysis

CVE-2023-40550 is exploitable with local system access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.

Attack Vector:
LOCAL
Attack Complexity:
LOW
Privileges Required:
LOW
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
NONE
Availability Impact:
NONE

Timeline

Reported to Red Hat.

Made public.

Weakness Type

Out-of-bounds Read

The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.


Products Associated with CVE-2023-40550

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2023-40550 are published in these products:

Red Hat Shim
 
Red Hat Enterprise Linux (RHEL)
 
Fedora Project Fedora
 
Red Hat Rhel Aus
 
Red Hat Rhel E4s
 
Red Hat Rhel Tus
 
Red Hat Rhel Eus
 

Affected Versions

Red Hat Enterprise Linux 7: Red Hat Enterprise Linux 7: Red Hat Enterprise Linux 8: Red Hat Enterprise Linux 8.2 Advanced Update Support: Red Hat Enterprise Linux 8.2 Telecommunications Update Service: Red Hat Enterprise Linux 8.2 Update Services for SAP Solutions: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support: Red Hat Enterprise Linux 8.4 Telecommunications Update Service: Red Hat Enterprise Linux 8.4 Update Services for SAP Solutions: Red Hat Enterprise Linux 8.6 Extended Update Support: Red Hat Enterprise Linux 8.8 Extended Update Support: Red Hat Enterprise Linux 8.8 Extended Update Support: Red Hat Enterprise Linux 9: Red Hat Enterprise Linux 9.0 Extended Update Support: Red Hat Enterprise Linux 9.0 Extended Update Support: Red Hat Enterprise Linux 9.0 Extended Update Support: Red Hat Enterprise Linux 9.2 Extended Update Support:

Exploit Probability

EPSS
0.02%
Percentile
6.30%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.