CVE-2026-68470 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: validate extension-frame layout before RX
Extension frames only have the extension header at the regular 802.11 header offset. The generic RX path can still reach helpers and interface dispatch code that read regular header address fields before unsupported extension subtypes are dropped.
mac80211 currently only handles S1G beacon extension frames. Drop other extension subtypes before they can reach regular-header RX processing. For S1G beacons, linearize the SKB with the management-frame path and require the fixed S1G beacon header, including optional fixed fields indicated by frame control, before generic RX dispatch.
Route S1G beacons through the station/default-link RX path without regular-header station lookup. Avoid regular-header address reads in the mac80211 RX paths that process S1G extension beacons, including accept-frame, duplicate-detection, address-copy, and MLO address-translation paths.
Also make ieee80211_get_bssid() length-safe before returning the S1G source-address pointer.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability addressed in this linux kernel update relates to improper validation of extension frame layouts within the mac80211 wireless subsystem. This issue occurs when processing 80211 extension frames that contain only an extension header at the standard 80211 header offset without proper validation before being processed by the generic receive path. The flaw exists because the current implementation allows unsupported extension subtypes to traverse regular header processing code paths before being dropped, creating potential attack vectors through malformed frame handling.
The technical implementation defect stems from the mac80211 subsystem's failure to properly validate extension frame structures prior to dispatching them through standard receive processing pipelines. While the subsystem correctly handles S1G beacon extension frames, it does not adequately filter other extension subtypes that could contain malicious payloads or cause unexpected behavior during regular header field access operations. This vulnerability represents a classic case of insufficient input validation leading to potential privilege escalation or denial-of-service conditions.
The operational impact of this vulnerability extends across wireless networking functionality within linux systems, particularly affecting devices utilizing the mac80211 framework for 80211 wireless communications. Attackers could potentially exploit this flaw by crafting malicious extension frames that bypass initial validation checks, allowing them to reach processing paths that expect standard 80211 header structures. This could result in memory corruption, system crashes, or unauthorized access to wireless network resources depending on the specific attack vector employed.
The mitigation strategy implemented addresses this vulnerability through multiple defensive layers including explicit filtering of unsupported extension subtypes before they reach generic RX processing code paths. The solution requires that S1G beacon frames be linearized with management-frame handling and validated against fixed S1G beacon headers including optional fields indicated by frame control bits. This approach prevents the problematic regular-header address field reads during S1G beacon processing while maintaining proper functionality for supported extension types.
The fix also implements specific routing changes that direct S1G beacons through station/default-link RX paths rather than standard header-based lookup mechanisms, eliminating potential access to regular-header fields in critical processing stages including accept-frame, duplicate-detection, address-copy, and MLO address-translation paths. Additionally, the ieee80211_get_bssid() function receives length-safe validation before returning S1G source-address pointers, preventing buffer overflows or memory access violations during address pointer handling operations.
This vulnerability aligns with CWE-129: Improper Validation of Array Index and CWE-787: Out-of-bounds Write patterns commonly found in wireless protocol implementations. The fix demonstrates adherence to secure coding practices by implementing early input validation and proper resource management before processing potentially malicious network frames. From an ATT&CK perspective, this addresses techniques related to privilege escalation through kernel exploitation and defense evasion via malformed frame injection attacks that target wireless subsystem vulnerabilities in operating system networking stacks.