CVE-2018-25368 in NordVPN
Summary
by MITRE • 05/26/2026
Nord VPN 6.14.31 contains a denial of service vulnerability that allows unauthenticated attackers to crash the application by submitting an excessively long string in the password field. Attackers can paste a buffer of repeated characters into the password input field to trigger an application crash when attempting to authenticate.
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Analysis
by VulDB Data Team • 05/26/2026
This vulnerability represents a classic buffer overflow condition that manifests as a denial of service attack against the nord vpn application version 6.14.31. The flaw occurs when the application fails to properly validate input length in the password field during authentication processes, creating an opportunity for malicious actors to exploit the system through malformed input sequences. The vulnerability specifically affects the authentication module where user credentials are processed, making it a critical point of entry for attackers seeking to disrupt service availability. This issue directly relates to common software security weaknesses documented in the common weakness enumeration database under cwe-121, which describes buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The attack vector is particularly concerning because it requires no authentication credentials to execute, making it accessible to any attacker with network access to the application interface. When an attacker submits an excessively long string containing repeated characters into the password field, the application's memory management routines fail to handle the oversized input properly, resulting in a crash of the authentication process and subsequent application instability. The operational impact extends beyond simple service disruption as this vulnerability can be leveraged to create persistent denial of service conditions that may require manual intervention to restore normal application functionality. The vulnerability demonstrates a fundamental lack of input validation controls within the application's credential processing pipeline, which is a core requirement specified in various security frameworks including the iso 27001 standard for information security management. Attackers can readily exploit this weakness using automated tools that generate long string inputs, potentially amplifying the impact through repeated attack attempts or integration into larger attack campaigns. The memory corruption resulting from this vulnerability creates an unstable application state that can lead to additional system instability or potentially more severe security consequences if the buffer overflow extends beyond simple application termination. Network security professionals should note that this vulnerability aligns with attack patterns documented in the mitre attack framework under the initial access and execution phases where adversaries establish footholds through application-level vulnerabilities. The lack of proper input sanitization in this authentication flow represents a significant security gap that undermines the application's integrity and availability. Organizations using this version of nord vpn should immediately implement mitigations including input length restrictions, enhanced authentication logging, and application monitoring to detect and prevent exploitation attempts. The vulnerability serves as a reminder of the critical importance of implementing proper bounds checking and input validation mechanisms throughout all application components, particularly those handling user authentication data. Security teams should also consider implementing intrusion detection systems that can identify suspicious input patterns and automated response mechanisms to prevent exploitation attempts from succeeding. The technical implementation of this vulnerability highlights the need for comprehensive security testing including fuzzing techniques that can identify similar buffer overflow conditions in other application components. This weakness underscores the importance of following secure coding practices and adhering to established security standards to prevent similar vulnerabilities from occurring in future software releases.