Description Preview
CVE-2021-20237 affects ZeroMQ versions prior to 4.3.3, specifically in the src/xpub.cpp component. The vulnerability is an uncontrolled resource consumption flaw (CWE-401) that manifests as a memory leak. When CURVE/ZAP authentication is disabled on a ZeroMQ server, remote unauthenticated attackers can exploit this vulnerability by sending specially crafted PUB messages that cause excessive memory consumption. This can eventually lead to a denial of service condition as system resources are exhausted. The vulnerability primarily impacts system availability.
Overview
ZeroMQ (libzmq) is a high-performance asynchronous messaging library used in distributed or concurrent applications. The vulnerability exists in the XPUB socket implementation where memory allocation occurs without proper deallocation when processing certain message patterns. When a server has CURVE/ZAP authentication disabled, which is a common configuration in some environments, it becomes vulnerable to this attack. An attacker can repeatedly send crafted messages that trigger the memory leak, gradually consuming all available system memory and potentially causing the application or entire system to become unresponsive.
Remediation
- Update ZeroMQ to version 4.3.3 or later which contains the fix for this vulnerability.
- If immediate updating is not possible, enable CURVE/ZAP authentication on all ZeroMQ servers as a mitigation measure.
- Implement network-level access controls to restrict who can connect to ZeroMQ servers.
- Monitor system memory usage for unexpected growth which might indicate exploitation attempts.
- Consider implementing application-level resource limits to prevent excessive memory consumption.
References
- Red Hat Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1921989
- GitHub Security Advisory: https://github.com/zeromq/libzmq/security/advisories/GHSA-4p5v-h92w-6wxw
- CWE-401: Improper Release of Memory Before Removing Last Reference
- ZeroMQ GitHub Repository: https://github.com/zeromq/libzmq
Industry ExposureMost to leastThis section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.
This section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.
- ManufacturingManufacturing
- Health Care & Social AssistanceHealth Care & Social Assistance
- Professional, Scientific, & Technical ServicesProfessional, Scientific, & Technical Services
- Educational ServicesEducational Services
- Finance and InsuranceFinance and Insurance
- Public AdministrationPublic Administration
- InformationInformation
- Management of Companies & EnterprisesManagement of Companies & Enterprises
- Retail TradeRetail Trade
- Transportation & WarehousingTransportation & Warehousing
- UtilitiesUtilities
- Arts, Entertainment & RecreationArts, Entertainment & Recreation
- Other Services (except Public Administration)Other Services (except Public Administration)
- Accommodation & Food ServicesAccommodation & Food Services
- Administrative, Support, Waste Management & Remediation ServicesAdministrative, Support, Waste Management & Remediation Services
- Agriculture, Forestry Fishing & HuntingAgriculture, Forestry Fishing & Hunting
- ConstructionConstruction
- MiningMining
- Real Estate Rental & LeasingReal Estate Rental & Leasing
- Wholesale TradeWholesale Trade