CVE-2021-25217 : Vulnerability Insights and Analysis

A buffer overrun in lease file parsing code in ISC DHCP can be exploited to affect dhcpd and dhclient.

Understanding CVE-2021-25217

This CVE involves a vulnerability in ISC DHCP that could lead to various outcomes depending on the affected component and system architecture.

What is CVE-2021-25217?

The vulnerability affects ISC DHCP versions 4.1-ESV-R1 to 4.1-ESV-R16 and 4.4.0 to 4.4.2. It allows attackers to trigger a buffer overrun by reading a lease file, impacting network connectivity.

The Impact of CVE-2021-25217

The vulnerability could crash the dhclient or dhcpd process, causing network connectivity issues or service disruptions for clients. Exploitation depends on the system architecture and compiler flags used.

Technical Details of CVE-2021-25217

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The flaw resides in the code used to parse stored leases, potentially enabling attackers to exploit discrepancies in parsing encapsulated option information.

Affected Systems and Versions

ISC DHCP versions 4.1-ESV to 4.1-ESV-R16-P1 and 4.4 to 4.4.2-P1 are affected by this vulnerability.

Exploitation Mechanism

Depending on the component attacked and the system architecture, attackers can trigger a crash in dhclient or dhcpd by reading a malicious lease file.

Mitigation and Prevention

To mitigate the risk associated with CVE-2021-25217, consider the following steps.

Immediate Steps to Take

No workarounds are currently known. Immediate action involves upgrading to the patched releases:

ISC DHCP 4.1-ESV-R16-P1
ISC DHCP 4.4.2-P1

Long-Term Security Practices

Maintain regular updates and security patches for ISC DHCP to prevent potential vulnerabilities.

Patching and Updates

Regularly check for security advisories and apply relevant patches or updates to keep ISC DHCP secure.