CVE-2026-80667 in Linux
Summary
by MITRE • 08/28/2026
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5: LAG, MPESW, Fix missing complete() on devcom error
mlx5_mpesw_work() returned without calling complete() when mlx5_lag_get_devcom_comp() returned NULL. A caller that queued the work and waited on mpesww->comp would block indefinitely.
Funnel the early-return path through a new "complete" label so the waiter is always woken.
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Analysis
by VulDB Data Team • 08/28/2026
The Linux kernel vulnerability identified in the mlx5 network driver involves a synchronization flaw within the Link Aggregation Group (LAG) and Multi-Purpose Ethernet Switch (MPESW) subsystems. Specifically, the function mlx5_mpesw_work() contains an error handling path that fails to invoke the complete() primitive when the helper function mlx5_lag_get_devcom_comp() returns NULL. This omission creates a race condition where a thread waiting for synchronization signals from this work item will remain blocked indefinitely because the expected completion event is never signaled. The root cause lies in the control flow logic of the driver, which allows an early exit without ensuring that all waiters are notified of the operation's termination or failure state.
From a technical perspective, this issue represents a classic violation of synchronization protocol expectations within kernel space operations. When a worker thread queues work and another entity waits on a completion structure, there is an implicit contract that the waiting thread will eventually be woken up to proceed with its execution flow. By returning without calling complete(), the driver leaves the system in a state where resources are held or threads are suspended unnecessarily. This behavior can lead to resource exhaustion as blocked threads consume kernel stack space and scheduler overhead without making progress, potentially degrading overall system performance or causing specific network interface functionalities to become unresponsive until a reboot occurs.
The operational impact of this vulnerability is primarily related to service availability and system stability for systems utilizing Mellanox ConnectX adapters configured with LAG or MPESW features. Administrators may experience hanging processes or applications that depend on the successful initialization or reconfiguration of these network interfaces. In worst-case scenarios, if multiple such operations are attempted concurrently or repeatedly, the accumulation of blocked threads could contribute to broader system instability, although it is generally classified as a denial-of-service condition rather than a privilege escalation vector. The flaw does not appear to allow for arbitrary code execution but significantly affects the reliability and predictability of network stack operations under error conditions.
To mitigate this vulnerability, users must apply the specific kernel patch that refactors the mlx5_mpesw_work() function to funnel all exit paths through a dedicated label responsible for calling complete(). This ensures that regardless of whether the devcom component is successfully retrieved or not, the synchronization mechanism is properly finalized and waiting threads are woken up. System administrators should update their Linux kernels to versions containing this fix. Additionally, monitoring tools can be configured to detect abnormal thread states or high CPU usage associated with network driver initialization loops as an indicator of potential exposure before patches are applied in environments where immediate updates are not feasible.
This vulnerability aligns with CWE-404, which describes improper resource shutdown or release leading to resource leaks and denial of service, specifically through the failure to signal completion events correctly. In terms of adversarial tactics, this flaw could be leveraged within the MITRE ATT&CK framework under T1496, Resource Hijacking, where an attacker might attempt to exhaust system resources by triggering repeated failures in network interface configurations that rely on these synchronization primitives. Understanding this context helps security teams prioritize patching efforts for critical infrastructure components dependent on stable kernel networking subsystems.