SEV-ES Bounds Check Failure Corrupts RMP, Compromise SNP
CVE-2021-26409 Published on January 11, 2023

Insufficient bounds checking in SEV-ES may allow an attacker to corrupt Reverse Map table (RMP) memory, potentially resulting in a loss of SNP (Secure Nested Paging) memory integrity.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2021-26409 can be exploited 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 be very high.

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

Weakness Type

What is a Classic Buffer Overflow Vulnerability?

The program copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. A buffer overflow condition exists when a program attempts to put more data in a buffer than it can hold, or when a program attempts to put data in a memory area outside of the boundaries of a buffer. The simplest type of error, and the most common cause of buffer overflows, is the "classic" case in which the program copies the buffer without restricting how much is copied. Other variants exist, but the existence of a classic overflow strongly suggests that the programmer is not considering even the most basic of security protections.

CVE-2021-26409 has been classified to as a Classic Buffer Overflow vulnerability or weakness.


Products Associated with CVE-2021-26409

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Affected Versions

AMD 3rd Gen EPYC Version various is affected by CVE-2021-26409

Exploit Probability

EPSS
0.06%
Percentile
17.74%

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.