CVE-2026-69185 in Socket.io
Summary
by MITRE • 08/03/2026
Socket.IO enables bidirectional and low-latency communication for every platform. Prior to 4.2.7, 3.4.5, and 3.3.6, a specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory. This vulnerability is fixed in 4.2.7, 3.4.5, and 3.3.6.
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Analysis
by VulDB Data Team • 08/03/2026
Socket.IO represents a critical real-time communication framework widely adopted across web applications for enabling bidirectional data exchange between clients and servers. The vulnerability analyzed here stems from inadequate validation of binary attachment handling within Socket.IO packet processing mechanisms. This flaw exists in versions prior to 4.2.7, 3.4.5, and 3.3.6, creating a significant memory exhaustion risk that can be exploited through carefully crafted malicious packets.
The technical nature of this vulnerability involves the manipulation of binary attachment handling within Socket.IO protocol implementation. Attackers can construct specially formatted packets that instruct the server to prepare for an excessive number of binary attachments while simultaneously buffering these elements in memory. The flaw lies in the absence of proper bounds checking and resource allocation limits during packet processing, allowing attackers to overwhelm server memory resources through controlled exploitation. This represents a classic denial-of-service vector that leverages the legitimate functionality of the framework against itself.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential system instability and resource exhaustion across affected deployments. Servers running vulnerable versions of Socket.IO become susceptible to memory starvation attacks where malicious actors can consume available RAM resources until the system becomes unresponsive or crashes entirely. This vulnerability particularly affects applications that process large volumes of binary data or those with limited memory resources, making it especially dangerous in cloud environments or systems with constrained computational capacity.
From a cybersecurity perspective, this vulnerability aligns with CWE-400, which addresses unchecked resource consumption, and maps to attack patterns described in the MITRE ATT&CK framework under privilege escalation and denial-of-service techniques. The exploitability of this flaw demonstrates how legitimate protocol features can be weaponized when proper input validation and resource management controls are absent. Organizations should prioritize immediate patching of affected Socket.IO versions and implement monitoring for unusual memory consumption patterns that might indicate exploitation attempts.
Security practitioners should consider implementing additional protective measures including connection rate limiting, packet size restrictions, and memory usage monitoring as supplementary defenses. The patched versions (4.2.7, 3.4.5, and 3.3.6) incorporate proper validation mechanisms that limit the number of concurrent binary attachments and implement appropriate timeout behaviors to prevent indefinite buffering operations. These updates represent essential security hardening measures that address fundamental protocol design weaknesses while maintaining backward compatibility with legitimate use cases.