exim exim CVE-2018-6789 vulnerability in Exim and Other Products
Published on February 8, 2018

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An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1. By sending a handcrafted message, a buffer overflow may happen. This can be used to execute code remotely.

Vendor Advisory Vendor Advisory NVD

Known Exploited Vulnerability

This Exim Buffer Overflow Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Issue in the base64d function in the SMTP listener in Exim before 4.90.1. By sending a handcrafted message, a buffer overflow may happen. This can be used to execute code remotely.

The following remediation steps are recommended / required by May 3, 2022: Apply updates per vendor instructions.

Vulnerability Analysis

CVE-2018-6789 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. It has the highest possible exploitability rating (3.9). The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.

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-2018-6789 has been classified to as a Classic Buffer Overflow vulnerability or weakness.


Products Associated with CVE-2018-6789

You can be notified by stack.watch whenever vulnerabilities like CVE-2018-6789 are published in these products:

Exim
 
Canonical Ubuntu Linux
 
Debian Linux
 

What versions are vulnerable to CVE-2018-6789?