CVE-2020-6072 in libmicrodns
Summary
by MITRE
An exploitable code execution vulnerability exists in the label-parsing functionality of Videolabs libmicrodns 0.1.0. When parsing compressed labels in mDNS messages, the rr_decode function's return value is not checked, leading to a double free that could be exploited to execute arbitrary code. An attacker can send an mDNS message to trigger this vulnerability.
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Analysis
by VulDB Data Team • 05/05/2026
The vulnerability identified as CVE-2020-6072 represents a critical code execution flaw within the Videolabs libmicrodns 0.1.0 library that processes multicast domain name system messages. This issue specifically targets the label-parsing functionality where the library handles compressed labels in mDNS packets, creating a pathway for remote code execution through improper error handling mechanisms. The vulnerability stems from a fundamental flaw in the rr_decode function's implementation where the return value from critical operations is not properly validated, leading to a cascading failure that manifests as a double free condition.
The technical exploitation of this vulnerability occurs when an attacker crafts and sends a specially crafted mDNS message containing malformed compressed labels to a target system running software that utilizes libmicrodns 0.1.0. During the parsing process, the library's failure to check the return value from the rr_decode function creates a scenario where memory deallocation operations are executed twice on the same memory block. This double free condition creates a predictable memory corruption state that can be leveraged by attackers to manipulate the program's execution flow. The vulnerability aligns with CWE-415, which specifically addresses double free conditions in memory management, and represents a classic example of how improper error handling can lead to arbitrary code execution in network services.
From an operational perspective, this vulnerability poses significant risks to systems that rely on mDNS for service discovery and network communication, particularly in enterprise environments where such protocols are commonly deployed. The remote nature of the attack vector means that exploitation can occur without requiring local system access or authentication, making it particularly dangerous in networked environments. Systems using libmicrodns 0.1.0 for mDNS processing are potentially vulnerable to attacks that could result in complete system compromise, data exfiltration, or denial of service conditions. The vulnerability affects the broader mDNS ecosystem and could impact various network services that depend on proper DNS resolution functionality, including but not limited to printer discovery, device enumeration, and local network service identification.
The mitigation strategy for CVE-2020-6072 requires immediate updates to the libmicrodns library to version 0.1.1 or later, which includes proper error handling for the rr_decode function and addresses the double free condition. Organizations should conduct comprehensive inventory assessments to identify all systems that utilize libmicrodns 0.1.0 and ensure that all affected applications are updated to prevent exploitation. Network administrators should also consider implementing monitoring for unusual mDNS traffic patterns that could indicate attempted exploitation attempts. The vulnerability demonstrates the importance of proper memory management practices and return value validation in network protocol implementations, aligning with ATT&CK technique T1059 for command and scripting interpreter usage, as attackers may leverage this vulnerability to establish persistent access through arbitrary code execution capabilities. Additionally, the issue highlights the necessity of robust input validation and error handling mechanisms in network-facing applications to prevent similar memory corruption vulnerabilities from being exploited in the future.