CVE-2026-12932 in OpenVPN
Summary
by MITRE • 07/30/2026
A memory leak in the tls-crypt-v2 client key extraction in OpenVPN 2.5.0 through 2.6.20 and 2.7_alpha1 through 2.7.4 allows remote attackers to cause a denial of service (memory exhaustion) via a flood of crafted packets
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Analysis
by VulDB Data Team • 07/30/2026
The vulnerability under discussion represents a critical memory management flaw within OpenVPN's implementation of tls-crypt-v2 protocol, specifically affecting client key extraction processes across multiple versions including 2.5.0 through 2.6.20 and 2.7_alpha1 through 2.7.4. This memory leak occurs during the processing of crafted packets that exploit improper handling of cryptographic key material in the tls-crypt-v2 framework, which is designed to provide additional security layers through encrypted control channel communications.
The technical implementation flaw stems from inadequate memory deallocation routines within the client key extraction mechanism where allocated memory blocks containing cryptographic keys and associated data structures are not properly freed after processing. When remote attackers send a flood of specially crafted packets that trigger this code path, each packet consumption results in memory allocation without corresponding deallocation, leading to progressive memory exhaustion on the target system. This issue manifests as a denial of service condition where the server gradually consumes all available memory resources, eventually causing system instability or complete service unavailability.
From an operational impact perspective, this vulnerability enables remote attackers to perform effective denial of service attacks against OpenVPN servers without requiring authentication or privileged access. The attack vector is particularly dangerous because it can be executed through network flooding with minimal resources, making it difficult to distinguish from legitimate traffic patterns. The memory exhaustion effect cascades through the system's resource management, potentially affecting other services running on the same infrastructure and creating broader operational disruptions beyond just the OpenVPN service itself.
The vulnerability aligns with CWE-401 which specifically addresses improper deallocation of memory, and maps to ATT&CK technique T1499.004 for network denial of service attacks through resource exhaustion. Organizations using affected OpenVPN versions should immediately implement mitigations including upgrading to patched versions, implementing rate limiting on incoming connections, and deploying network monitoring to detect anomalous packet flooding patterns. Additionally, system administrators should configure memory limits and monitoring alerts to detect early signs of memory exhaustion, while the affected implementations should be prioritized for immediate patch deployment following vendor advisories and security bulletins.