CVE-2020-1730 in MySQL Workbench
Summary
by MITRE
A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat from this vulnerability is system availability.
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Analysis
by VulDB Data Team • 05/16/2025
The vulnerability identified as CVE-2020-1730 represents a critical denial of service flaw within the libssh library ecosystem, affecting versions prior to 0.8.9 and 0.9.4. This weakness specifically manifests in the improper handling of AES-CTR and DES cipher operations during connection termination phases. The flaw occurs when the system attempts to clean up cipher resources while a connection remains in an uninitialized state, creating a scenario where normal operational procedures trigger unexpected system crashes. This vulnerability falls under the category of improper handling of resources during cleanup operations, which aligns with CWE-415 and CWE-416 as referenced in the Common Weakness Enumeration framework. The root cause stems from insufficient validation of connection state before attempting cryptographic resource deallocation, particularly when dealing with cipher contexts that have not yet been fully established.
The operational impact of CVE-2020-1730 extends beyond simple service disruption to encompass broader system availability concerns that can severely compromise network infrastructure reliability. When exploited, this vulnerability allows attackers to induce system crashes through carefully crafted connection termination sequences, effectively rendering affected systems unavailable to legitimate users. The threat landscape for this vulnerability aligns with ATT&CK technique T1499.004, which addresses network denial of service attacks targeting system availability. Organizations relying on libssh for secure communications face significant risk of operational disruption, as the vulnerability can be triggered without requiring authentication or advanced privileges. The crash conditions typically manifest as segmentation faults or memory access violations during connection teardown, making it particularly dangerous in production environments where continuous availability is paramount.
Mitigation strategies for CVE-2020-1730 primarily focus on immediate version upgrades to libssh 0.8.9 or 0.9.4, which contain the necessary patches to address the improper cipher cleanup handling. System administrators should prioritize deployment of these updated versions across all affected infrastructure, particularly in environments where SSH services are exposed to external networks. Additional defensive measures include implementing connection rate limiting and monitoring for unusual connection termination patterns that might indicate exploitation attempts. Network segmentation and access controls can help minimize the attack surface by limiting exposure of vulnerable systems to potential attackers. Security teams should also consider implementing intrusion detection systems capable of identifying suspicious SSH connection behavior patterns that could precede exploitation attempts. The vulnerability demonstrates how seemingly minor resource management flaws can create significant availability risks, emphasizing the importance of thorough testing of cleanup procedures and proper state validation in cryptographic libraries. Organizations should conduct comprehensive vulnerability assessments to identify all systems utilizing affected libssh versions and establish remediation schedules that minimize operational disruption while ensuring security compliance.