CVE-2026-40958 in Secure Access
Summary
by MITRE • 07/15/2026
CVE-2026-40958 is a input validation error in Secure Access clients prior to 14.55. Attackers with intimate knowledge of and total control over the tunnel protocol can create a non-persistent DoS against their client.
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Analysis
by VulDB Data Team • 07/15/2026
This vulnerability represents a critical input validation flaw within Secure Access client implementations preceding version 14.55, specifically targeting the tunnel protocol handling mechanisms. The weakness stems from inadequate validation of incoming data streams that traverse the secure communication channels, creating an exploitable condition where malicious actors can manipulate protocol messages to disrupt normal client operations. The vulnerability is classified as a non-persistent denial of service attack, meaning the impact does not persist beyond the initial exploitation event and does not result in permanent system compromise or data corruption.
The technical nature of this flaw allows attackers who possess intimate knowledge of the tunnel protocol specifications and maintain complete control over protocol communication to craft specially malformed input sequences that cause the client application to terminate unexpectedly or enter a non-functional state. This type of vulnerability typically occurs when the client application fails to properly sanitize or validate received data before processing it within the secure tunnel context, creating a path for malicious input to trigger abnormal program behavior. The attack vector specifically requires an attacker with deep protocol understanding and full control over communication channels, making it less likely to be exploited in casual scenarios but still dangerous in targeted environments.
The operational impact of this vulnerability extends beyond simple service disruption, as it can affect the reliability and availability of secure communication channels that organizations depend upon for critical operations. When a client experiences denial of service due to this flaw, users may lose access to secured resources or services until the client is manually restarted or the system is rebooted. The non-persistent nature means that while the immediate impact is contained, repeated exploitation attempts can cause cumulative operational issues and potentially disrupt business continuity if not addressed promptly. Security teams must consider this vulnerability as part of their broader threat landscape assessment when evaluating secure access solutions.
Organizations should prioritize immediate remediation through patch management procedures to upgrade affected Secure Access clients to version 14.55 or later, which contains the necessary input validation fixes. Additionally, implementing network monitoring solutions that can detect anomalous protocol behavior patterns may help identify exploitation attempts before they cause significant disruption. The vulnerability aligns with CWE-20, which covers "Improper Input Validation," and represents a specific implementation weakness that could be mapped to ATT&CK technique T1498, focusing on network denial of service attacks. Security controls should also include limiting access to tunnel protocol interfaces and implementing robust logging mechanisms to track potential exploitation attempts and maintain audit trails for incident response activities.