CVE-2019-11937 in Mcrouter
Summary
by MITRE
In Mcrouter prior to v0.41.0, a large struct input provided to the Carbon protocol reader could result in stack exhaustion and denial of service.
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Analysis
by VulDB Data Team • 03/07/2024
The vulnerability identified as CVE-2019-11937 affects Mcrouter versions prior to v0.41.0, representing a critical stack exhaustion issue within the Carbon protocol reader component. This flaw manifests when the system processes large struct input data, creating a scenario where the stack memory becomes depleted through excessive recursive or iterative processing operations. The Carbon protocol is commonly used for communication between memcached clients and servers, making this vulnerability particularly concerning for distributed caching systems that rely on Mcrouter for traffic management and routing.
The technical implementation of this vulnerability stems from insufficient input validation and memory management within the Carbon protocol parser. When malformed or excessively large struct data is received, the parser fails to properly constrain stack usage during processing, leading to stack overflow conditions. This behavior aligns with CWE-772, which addresses insufficient resource management, and specifically relates to stack-based buffer overflows that occur when recursive functions or deep call stacks are not properly bounded. The vulnerability exploits the inherent memory allocation patterns of the parser, where each recursive call or iterative processing step consumes stack space without adequate bounds checking.
The operational impact of CVE-2019-11937 extends beyond simple denial of service, as it can be leveraged by attackers to disrupt critical caching infrastructure. Systems utilizing Mcrouter for memcached traffic management become vulnerable to sustained denial of service attacks, potentially affecting thousands of concurrent connections and causing cascading failures across dependent services. The vulnerability operates at the protocol level, making it particularly difficult to detect and mitigate through traditional network security measures, as it appears as legitimate traffic that simply consumes excessive resources. This characteristic places the vulnerability in the ATT&CK matrix under T1499.004 for Network Denial of Service, where adversaries can exhaust system resources to prevent legitimate use.
Mitigation strategies for this vulnerability require immediate patching to version v0.41.0 or later, which includes enhanced input validation and stack usage constraints within the Carbon protocol reader. Organizations should implement monitoring for unusual memory consumption patterns and establish automated alerting for stack overflow conditions. Network segmentation and rate limiting can provide additional defense in depth, while regular security assessments of protocol parsers should be conducted to identify similar resource exhaustion vulnerabilities. The fix addresses the root cause by implementing proper stack depth limiting and input size validation, preventing the recursive processing from consuming excessive memory resources and ensuring system stability under malicious input conditions.