CVE-2016-8706 in Memcached
Summary
by MITRE
An integer overflow in process_bin_sasl_auth function in Memcached, which is responsible for authentication commands of Memcached binary protocol, can be abused to cause heap overflow and lead to remote code execution.
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Analysis
by VulDB Data Team • 04/20/2025
The vulnerability identified as CVE-2016-8706 represents a critical integer overflow flaw within the Memcached binary protocol implementation that directly impacts the authentication handling mechanism. This vulnerability exists in the process_bin_sasl_auth function, which processes authentication commands for the Memcached server. The flaw occurs when the server processes certain authentication requests that contain malformed data, specifically in how it handles integer values during the authentication process. The integer overflow condition arises when the server attempts to calculate buffer sizes or memory allocation requirements based on user-supplied authentication data, leading to a scenario where the calculated values exceed the maximum representable integer value for the system architecture.
The technical exploitation of this vulnerability follows a specific pattern that leverages the integer overflow to manipulate heap memory allocation. When an attacker sends a specially crafted authentication request with manipulated data lengths, the server's authentication function performs arithmetic operations on these values that result in integer overflow. This overflow causes the system to allocate insufficient memory for the authentication buffer, which can then be overwritten through subsequent heap operations. The heap overflow creates a condition where attacker-controlled data can overwrite critical memory structures, potentially allowing for arbitrary code execution. This vulnerability is particularly dangerous because it operates at the binary protocol level, meaning that remote attackers can exploit it without requiring local system access or authentication to the Memcached service.
The operational impact of CVE-2016-8706 extends beyond simple remote code execution, as Memcached servers are commonly deployed in environments where they handle sensitive data and are often accessible from untrusted networks. The vulnerability affects systems where Memcached is configured to accept binary protocol connections and where SASL authentication is enabled, making it particularly relevant in web application environments where Memcached serves as a caching layer. Attackers can leverage this vulnerability to execute arbitrary code with the privileges of the Memcached process, potentially leading to complete system compromise, data exfiltration, or service disruption. The exploitability of this vulnerability is enhanced by the fact that Memcached often runs with elevated privileges and may be accessible from multiple network segments.
Mitigation strategies for CVE-2016-8706 should focus on immediate patching of affected Memcached versions, as the vulnerability was addressed through proper integer overflow checking in subsequent releases. Organizations should implement network segmentation to restrict access to Memcached servers, ensuring that only trusted systems can communicate with them. The use of firewall rules to limit access to the Memcached binary protocol ports, typically 11211, should be implemented alongside authentication mechanisms that do not rely on vulnerable SASL implementations. Additionally, monitoring for unusual authentication patterns and implementing intrusion detection systems can help identify exploitation attempts. This vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and represents a classic example of how improper input validation in protocol implementations can lead to memory corruption vulnerabilities. The ATT&CK framework categorizes this as a privilege escalation technique through memory corruption, where the initial access point may be through network-based attacks targeting the binary protocol interface, ultimately leading to full system compromise. Organizations should also consider implementing application-level firewalls or proxies that can filter and validate authentication requests before they reach the vulnerable Memcached instance.