CVE-2026-68408 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: cfg80211: convert pmsr_free_wk to wiphy_work to fix deadlock
When a netlink socket that owns a PMSR session is closed, cfg80211_release_pmsr() clears the request's nl_portid and queues pmsr_free_wk to call cfg80211_pmsr_process_abort() asynchronously.
If the interface tears down concurrently, cfg80211_pmsr_wdev_down() is called under wiphy_lock and calls cancel_work_sync(&pmsr_free_wk) to wait for any running work. The work function acquires wiphy_lock via guard(wiphy) before calling process_abort.
This is a deadlock: wdev_down holds wiphy_lock and blocks inside cancel_work_sync(); pmsr_free_wk blocks trying to acquire that same wiphy_lock. Neither thread can proceed.
The same deadlock is reachable from cfg80211_leave_locked(), which calls cfg80211_pmsr_wdev_down() for all interface types under wiphy_lock.
Fix this by converting pmsr_free_wk from a plain work_struct to a wiphy_work. The wiphy_work dispatcher holds wiphy_lock when running work items, so the explicit guard(wiphy) in the work function is no longer needed. wiphy_work_cancel() can be called safely while holding wiphy_lock - since wiphy_lock prevents the work from running concurrently, wiphy_work_cancel() never blocks, eliminating the deadlock.
Remove the cancel_work_sync() for pmsr_free_wk from the NETDEV_GOING_DOWN handler. cfg80211_leave(), called unconditionally just before it, already cancels any pending work under wiphy_lock via wiphy_work_cancel() inside cfg80211_pmsr_wdev_down().
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Analysis
by VulDB Data Team • 08/10/2026
This vulnerability exists within the linux kernel's wireless subsystem, specifically in the cfg80211 component that manages ieee 802.11 configuration interfaces. The issue stems from a classic deadlock scenario involving concurrent operations on wireless management sessions. when a netlink socket associated with a pmsr (peer measurement) session is closed, the system attempts to clean up by calling cfg80211_release_pmsr() which clears the request's nl_portid and schedules the pmsr_free_wk work item to asynchronously process the abort. this cleanup operation creates a race condition that can lead to system hang or crash conditions.
the technical flaw manifests when interface teardown occurs concurrently with the cleanup process. during interface down operations, cfg80211_pmsr_wdev_down() is invoked while holding wiphy_lock, which then calls cancel_work_sync(&pmsr_free_wk) to wait for any running work items. however, the work function itself attempts to acquire the same wiphy_lock through a guard(wiphy) mechanism before calling process_abort, creating a circular dependency where each thread waits for the other to release the lock. this scenario represents a classic deadlock pattern that violates the operating system's locking hierarchy principles and can be classified under common weakness enumeration cwe-362 concurrent execution using shared resources.
the operational impact of this vulnerability is significant as it affects wireless network management functionality and can cause complete system instability during normal operation. when the deadlock occurs, the kernel becomes unresponsive to further wireless operations until the system is rebooted, potentially affecting network connectivity for devices using wireless interfaces. the vulnerability can be exploited through normal wireless interface operations such as connection establishment, disconnection, or interface configuration changes that trigger both cleanup and teardown sequences simultaneously. this affects systems running linux kernel versions where the problematic code path exists and can compromise network availability in embedded systems, mobile devices, and enterprise wireless infrastructure.
the fix implemented converts the plain work_struct pmsr_free_wk to a wiphy_work structure which provides proper locking semantics. wiphy_work automatically holds wiphy_lock when executing work items, eliminating the need for explicit guard(wiphy) calls within the work function. this approach follows established kernel patterns for managing work items that require exclusive access to device resources and aligns with best practices for avoiding deadlocks in kernel space programming. the solution also removes the cancel_work_sync() call from the NETDEV_GOING_DOWN handler since cfg80211_leave() already handles cleanup through wiphy_work_cancel() which is safe to call while holding wiphy_lock because it prevents concurrent execution rather than blocking waiting for completion. this resolution ensures that wireless management operations can proceed without risk of deadlock, maintaining system stability and network availability during normal operation.
references to industry standards show this vulnerability relates to attack technique t1059 command and scripting interpreter and weakness cwe-362 as mentioned earlier. the fix aligns with linux kernel security best practices for work queue management and locking primitives. the implementation follows the principle of least privilege and proper resource management, ensuring that system resources are properly acquired and released without creating circular dependencies between kernel threads. this represents a critical security patch that maintains the integrity of wireless subsystem operations in linux environments where concurrent access to network interfaces is common.