CVE-2021-27645 : What You Need to Know
Learn about CVE-2021-27645, a critical vulnerability in the GNU C Library affecting versions 2.29 through 2.33. Understand the impact, technical details, and mitigation strategies to protect your systems.
A critical vulnerability with the nameserver caching daemon (nscd) in the GNU C Library (glibc) has been identified. Here's what you need to know about CVE-2021-27645.
Understanding CVE-2021-27645
This CVE pertains to a double-free vulnerability in the GNU C Library's nameserver caching daemon, which could lead to a Denial of Service attack on the local system.
What is CVE-2021-27645?
The nameserver caching daemon (nscd) in glibc versions 2.29 through 2.33 is affected by a double-free flaw while processing a request for netgroup lookup. Attackers can exploit this vulnerability to crash the daemon, potentially causing service degradation or Denial of Service.
The Impact of CVE-2021-27645
The impact of this vulnerability is significant as it can result in degraded service or Denial of Service on the local system, affecting the availability of network services.
Technical Details of CVE-2021-27645
Let's delve into the technical aspects of CVE-2021-27645 to understand the vulnerability better.
Vulnerability Description
The vulnerability arises from a double-free issue in the nameserver caching daemon of glibc versions 2.29 through 2.33 when processing netgroup lookup requests.
Affected Systems and Versions
All systems running glibc versions 2.29 through 2.33 are vulnerable to this issue. It is crucial to identify and patch these versions promptly.
Exploitation Mechanism
By sending specially crafted requests for netgroup lookup, malicious actors can trigger the double-free vulnerability in the glibc nameserver caching daemon, leading to a potential Denial of Service condition.
Mitigation and Prevention
To safeguard your systems from CVE-2021-27645, follow these mitigation strategies.
Immediate Steps to Take
Immediately update glibc to a patched version that addresses the double-free vulnerability. Monitor system logs for any unusual activity that might indicate exploitation attempts.
Long-Term Security Practices
Regularly update system libraries and software to prevent known vulnerabilities from being exploited. Implement network security measures to detect and block malicious traffic.
Patching and Updates
Stay informed about security updates released by the GNU C Library and promptly apply patches to address critical vulnerabilities like CVE-2021-27645.