CVE-2026-78127 in strongSwan
Summary
by MITRE • 09/11/2026
libcharon in strongSwan 4.1.2 through 6.0.7 has a missing release of memory after its effective lifetime in the IKE message parser.
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Analysis
by VulDB Data Team • 09/11/2026
The vulnerability identified within libcharon, the core library component of the strongSwan open-source implementation of Internet Key Exchange (IKE) and IPsec protocols, represents a critical resource management flaw affecting versions 4.1.2 through 6.0.7. This issue is classified as a memory leak resulting from a missing release of allocated memory after its effective lifetime has concluded within the IKE message parser module. In complex network security applications like strongSwan, efficient memory handling is paramount to maintaining system stability and preventing denial-of-service conditions. The specific flaw occurs during the parsing phase of incoming or outgoing IKE messages, where dynamic memory allocation functions are invoked to process packet data structures but fail to trigger corresponding deallocation routines upon completion of processing or in error paths.
From a technical perspective, this defect aligns with CWE-401, which describes missing release of memory after effective lifetime. The root cause lies in the control flow logic within the IKE parser, where certain execution branches do not properly invoke free() or equivalent cleanup functions for heap-allocated buffers used to store parsed message components. This oversight can be triggered by specific malformed packets or under high-load conditions where rapid parsing cycles occur without adequate garbage collection of transient objects. Over time, as the daemon processes numerous IKE negotiations, these unreleased memory blocks accumulate in the process address space, leading to a gradual but steady increase in RAM consumption.
The operational impact of this vulnerability is primarily centered on resource exhaustion and potential service degradation or failure. As the memory leak progresses, the strongSwan daemon consumes an increasing amount of system resources until it either triggers operating-level out-of-memory killers or causes the application itself to crash due to allocation failures. This effectively results in a Denial of Service (DoS) condition for IPsec connectivity managed by that instance. For environments relying on continuous VPN tunnels, such as enterprise remote access or site-to-site connections, this can lead to intermittent disconnections and loss of secure communication channels until the service is manually restarted. Furthermore, if an attacker can induce rapid parsing cycles through crafted packets, they may accelerate this exhaustion process, turning a slow leak into a more immediate availability threat.
In terms of industry standard mapping, this vulnerability corresponds to MITRE ATT&CK technique T1499, Endpoint Denial of Service, specifically under the sub-technique of Resource Exhaustion: OOM. It also relates to CWE-770, Allocation of Resources Without Limits or Throttling, as the unbounded growth of memory usage lacks internal safeguards against excessive consumption during normal operation. The flaw underscores the importance of rigorous static analysis and dynamic testing in network daemon development, particularly for components handling untrusted input from external networks like IKE parsers which are frequently targeted by malicious actors seeking to disrupt infrastructure availability.
Mitigation strategies involve upgrading strongSwan to a version beyond 6.0.7 where this memory management issue has been addressed through code patches that ensure proper deallocation in all execution paths, including error handling routines. Administrators should also implement monitoring solutions that track the memory footprint of the charon process over time to detect early signs of leakage before it impacts service availability. In interim scenarios where immediate patching is not feasible, configuring automatic restart policies for the strongSwan daemon can serve as a temporary compensating control to reset memory usage periodically and maintain operational continuity until the underlying code defect is resolved by upstream developers.