CVE-2026-72308 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
mlxsw: fix refcount leak in mlxsw_sp_port_lag_join()
When mlxsw_sp_port_lag_index_get() fails, mlxsw_sp_port_lag_join() returns an error without releasing the lag reference obtained by the earlier mlxsw_sp_lag_get(). All other error paths in the function jump to the cleanup label that ends with mlxsw_sp_lag_put(), so this is a single missed release.
Fix the leak by replacing the bare 'return err' with a goto to the existing error cleanup label, which will drop the reference safely.
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability exists within the mlxsw network driver subsystem of the Linux kernel, specifically affecting the mlxsw_sp_port_lag_join() function that manages link aggregation group operations. The issue represents a classic reference counting error that can lead to resource exhaustion and potential system instability. When the mlxsw_sp_port_lag_index_get() function fails during port joining operations, the code path does not properly release the previously acquired lag reference through mlxsw_sp_lag_get(), creating a memory leak scenario.
The technical flaw manifests as a missing reference count decrement in a specific error handling pathway. The function implements proper cleanup routines for all other error conditions through a dedicated goto cleanup label that correctly executes mlxsw_sp_lag_put() to release the reference. However, when mlxsw_sp_port_lag_index_get() returns an error, the code simply executes a bare return err statement without invoking the cleanup mechanism. This creates a scenario where the lag reference remains incremented while the function exits, effectively leaking one reference count per occurrence.
The operational impact of this vulnerability extends beyond simple memory consumption as it can lead to progressive resource depletion in systems handling high volumes of link aggregation operations. Network administrators may observe system performance degradation, increased memory usage, or even potential system crashes under sustained load conditions where multiple port joining operations fail consecutively. The leak becomes particularly problematic in environments with dynamic network topology changes or automated network management systems that frequently manipulate link aggregation groups.
This vulnerability aligns with CWE-401, which specifically addresses improper release of memory and resources, and demonstrates characteristics consistent with the ATT&CK technique T1490, where adversaries may exploit resource exhaustion vulnerabilities to disrupt system operations. The fix implements a straightforward but critical correction by modifying the error return path to utilize the existing cleanup mechanism through a goto statement that properly invokes mlxsw_sp_lag_put(). This approach ensures consistent reference counting behavior across all code paths and maintains proper resource management throughout the function's execution lifecycle, aligning with kernel development best practices for memory safety and resource management.
The remediation strategy demonstrates proper defensive programming principles by ensuring all acquisition operations have corresponding release mechanisms, regardless of execution path. This fix prevents the accumulation of unreleased references that could eventually exhaust available resources or cause subsystem instability. The solution maintains backward compatibility while strengthening the driver's robustness against error conditions that might occur during dynamic network configuration operations, particularly in data center environments where link aggregation groups are frequently modified.