CVE-2026-76235 in Red Hat
Summary
by MITRE • 08/19/2026
A memory leak flaw was found in cockpit-ws. The login page handler leaks a heap allocation on every unauthenticated request that carries a CockpitLang cookie, allowing a remote unauthenticated attacker to exhaust memory on the host and cause a denial of service.
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Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified within the cockpit-ws component represents a classic resource management failure characterized by a persistent memory leak in the web server's authentication handling logic. This flaw specifically manifests when processing incoming HTTP requests that include a CockpitLang cookie but lack valid authentication credentials. In such scenarios, the application allocates heap memory to handle the request context or parse the language preference data but fails to properly release this allocation upon completion of the unauthenticated session cycle. Over time, as these specific types of requests accumulate, typically through automated scanning tools or persistent malicious actors, the server's available memory is progressively consumed until system resources are exhausted.
From a technical perspective, this issue aligns with CWE-401, which describes missing release of memory after effective usage. The root cause lies in the application logic where the cleanup routines for heap allocations associated with unauthenticated sessions containing specific cookie attributes are either bypassed or omitted entirely. This oversight means that every request carrying the CockpitLang header without subsequent successful authentication contributes to a steady increase in the process's working set size. In environments running cockpit-ws, which often serves as a critical interface for system administration and container management, such resource exhaustion can have severe operational consequences beyond simple application instability.
The primary impact of this vulnerability is a denial of service condition resulting from memory exhaustion. As the heap usage grows unchecked, the operating system may begin to swap heavily or invoke its Out-Of-Memory killer mechanisms, potentially terminating not only the cockpit-ws process but also other critical services running on the same host. This leads to a complete loss of availability for remote management capabilities and can disrupt dependent applications sharing the server's resources. Since the attack vector requires no prior authentication, it is particularly dangerous as it allows any external actor with network access to degrade system stability without needing valid credentials or exploiting complex logic flaws in authenticated workflows.
This vulnerability maps directly to MITRE ATT&CK technique T1498, specifically Network Denial of Service via resource exhaustion. The attacker leverages the application's failure to manage resources correctly during unauthenticated interactions to achieve service disruption. To mitigate this risk, immediate patching is required as soon as an official update from the cockpit-ws maintainers becomes available that addresses the memory leak in the login handler. In the interim, network-level controls such as rate limiting on authentication endpoints can help reduce the volume of requests processed by the vulnerable code path. Additionally, implementing strict monitoring for heap usage trends and configuring automatic restart policies or resource quotas at the container or system level can provide a layer of resilience against accidental or malicious memory exhaustion until the underlying software defect is resolved.