CVE-2026-98338 in Linux
Summary
by MITRE • 10/06/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: cfg80211: ibss: ref BSS entry for joined event
When the IBSS is joined, we only record the BSSID/channel in the event and look up the BSS entry when processing it. However, that's racy, e.g. a new scan with NL80211_SCAN_FLAG_FLUSH can remove it, causing a warning in the event work:
!bss WARNING: net/wireless/ibss.c:37 at __cfg80211_ibss_joined+0x3d3/0x440 Workqueue: cfg80211 cfg80211_event_work cfg80211_process_wdev_events+0x39f/0x5b0 net/wireless/util.c:1144 cfg80211_process_rdev_events+0xa1/0x110 net/wireless/util.c:1179 cfg80211_event_work+0x2f/0x40 net/wireless/core.c:393
Do the lookup early (the driver is expected to only join an IBSS that has a BSS entry) and keep a reference to it.
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Analysis
by VulDB Data Team • 10/06/2026
The Linux kernel wireless subsystem contains a race condition vulnerability within the Independent Basic Service Set implementation of cfg80211, specifically affecting how network interface events are processed during station association. This flaw arises from an inconsistent handling of Base Station identifier references when joining an IBSS network. Under normal operation, when a device joins an IBSS, the kernel records only the BSSID and channel information in the event structure rather than retaining a direct reference to the underlying BSS entry object. The actual lookup for this BSS entry is deferred until the event workqueue processes it later. This asynchronous approach creates a critical window of vulnerability where the state of the network environment can change before the event handler executes, leading to potential data integrity issues and system instability.
The core technical flaw lies in the timing mismatch between event generation and event processing. Because the BSS entry lookup is delayed, concurrent operations such as new scans initiated with NL80211_SCAN_FLAG_FLUSH can remove or invalidate the specific BSS entry that was originally associated with the join event. When the cfg80211_event_work eventually attempts to process this stale reference, it fails to find the expected object in the network namespace. This failure triggers a kernel warning within net/wireless/ibss.c at the __cfg80211_ibss_joined function, indicating that the bss pointer is null or invalid. While this specific instance manifests as a warning rather than an immediate crash, it represents a significant reliability issue and can lead to undefined behavior if subsequent operations assume the existence of valid network structures.
From a security perspective, this vulnerability aligns with CWE-362, which describes concurrent execution errors resulting in race conditions. The lack of proper synchronization between the event creation phase and the processing phase allows external stimuli, such as scan requests from user space or other kernel subsystems, to alter shared state unexpectedly. In the context of MITRE ATT&CK, this relates to techniques involving resource manipulation where an attacker could potentially influence network configuration states by triggering scans at precise moments during association processes. Although direct exploitation for remote code execution is unlikely given the nature of the warning, such race conditions can be leveraged in denial-of-service scenarios or as part of a larger attack chain to disrupt wireless connectivity and stability on affected systems.
The operational impact includes degraded system reliability due to kernel warnings cluttering logs and potential instability if the null pointer dereference were to escalate into a panic under different configurations or stress tests. It also affects the consistency of network state reporting, potentially leading applications relying on cfg80211 events to receive incorrect information about connected networks. For administrators and developers, this highlights the importance of maintaining reference counts for critical kernel objects during asynchronous operations to ensure that resources remain valid throughout their lifecycle.
The resolution involves modifying the ibss join logic to perform the BSS entry lookup immediately upon joining rather than deferring it. By securing a reference count on the BSS entry at the time of association, the system ensures that the object remains alive and accessible when the event workqueue processes it later. This change assumes that drivers only attempt to join IBSS networks for which a valid BSS entry already exists, thereby eliminating the race condition window entirely. To mitigate this issue in environments running affected kernel versions, users should apply the latest available security patches from their distribution vendors. Additionally, minimizing unnecessary scan operations during active network association phases can reduce exposure to similar timing-related issues until full patching is implemented.