CVE-2026-23246: 
Linux Kernel vulnerability analysis and mitigation

CVE-2026-23246 is a stack out-of-bounds write vulnerability in the Linux kernel's mac80211 WiFi subsystem, specifically in the ieee80211_ml_reconfiguration function. The flaw arises because link_id extracted from the ML Reconfiguration element can range from 0 to 15, but the link_removal_timeout[] array only contains 15 elements (indices 0–14), making index 15 out-of-bounds. Affected Linux kernel versions include 6.5.1–6.6.130, 6.7–6.12.77, 6.13–6.18.17, and 6.19–6.19.7. It was disclosed on March 18, 2026, and carries a CVSS v3.1 base score of 8.8 (High) (Red Hat Advisory, Red Hat Bugzilla).

The root cause is improper validation of an array index (CWE-129) in the ieee80211_ml_reconfiguration function within the Linux kernel's mac80211 subsystem. The link_id value is derived from a 4-bit field (control & 0x000f) in a received ML Reconfiguration management frame, yielding values 0–15, but the link_removal_timeout[] array is sized to IEEE80211_MLD_MAX_NUM_LINKS (15 elements, indices 0–14). When a subelement with link_id == 15 is processed, the kernel writes to an out-of-bounds stack location. The fix skips subelements where link_id >= IEEE80211_MLD_MAX_NUM_LINKS (Red Hat Bugzilla, Kernel Patch). Exploitation requires only adjacent network proximity with no authentication or user interaction.

Successful exploitation can result in a stack out-of-bounds write in kernel space, enabling an unauthenticated attacker in adjacent network range to achieve arbitrary code execution with kernel privileges or cause a denial of service (system crash). All three security dimensions are affected: confidentiality, integrity, and availability are rated High. Given kernel-level code execution, an attacker could fully compromise the affected host, potentially enabling lateral movement within the local network segment (Red Hat Advisory, Feedly Intelligence).

1. Reconnaissance: Identify systems running a vulnerable Linux kernel version (6.5.1–6.6.130, 6.7–6.12.77, 6.13–6.18.17, or 6.19–6.19.7) with WiFi interfaces enabled and Multi-Link Operation (MLO/802.11be) support active, from an adjacent network position.
2. Craft malicious ML Reconfiguration frame: Construct an 802.11 management frame containing an ML Reconfiguration element where the link_id field (bits 0–3 of the control field) is set to 15 (0x000f), which is the maximum 4-bit value.
3. Transmit the frame: Broadcast or unicast the crafted management frame to the target device over the wireless medium from an adjacent network position (no authentication required).
4. Trigger out-of-bounds write: The vulnerable ieee80211_ml_reconfiguration function processes the subelement without bounds-checking link_id, writing to link_removal_timeout[15] — one element beyond the 15-element array — corrupting adjacent kernel stack memory.
5. Achieve objective: Depending on the kernel stack layout and attacker-controlled data, this may result in a kernel panic (denial of service) or, with further exploitation techniques (e.g., stack pivoting, ROP chains), arbitrary kernel code execution (Red Hat Bugzilla, Feedly Intelligence).

• Network: Unexpected or malformed 802.11 management frames (specifically ML Reconfiguration frames) with link_id value of 15 observed on wireless interfaces; unusual management frame traffic from unknown MAC addresses in adjacent network range.
• Logs: Kernel oops, BUG, or stack corruption messages in /var/log/kern.log or dmesg output referencing ieee80211_ml_reconfiguration or mac80211; kernel panic traces involving WiFi subsystem stack frames.
• Process/System: Unexpected system reboots or kernel crashes on WiFi-enabled hosts; kernel WARN or BUG_ON triggers in mac80211 module logs.
• File System: Presence of kernel crash dump files (e.g., /var/crash/, vmcore) generated around the time of suspicious WiFi activity (Red Hat Bugzilla).

Update the Linux kernel to a patched version: 6.6.130 or later (for the 6.6 stable branch), 6.12.77 or later, 6.18.17 or later, 6.19.7 or later, or 7.0-rc2 or later. Patches are available in the upstream stable kernel repository (Kernel Patch). Distribution-specific updates have been issued by Red Hat, SUSE (SUSE-SU-2026:2217-1, SUSE-SU-2026:2238-1), and Debian (DSA-6238-1) (Red Hat Advisory, SUSE Advisory). As a temporary workaround where patching is not immediately feasible, disabling WiFi interfaces or restricting 802.11be/MLO management frame processing can reduce exposure.

Red Hat triaged the vulnerability and filed a Bugzilla entry classifying it as medium severity, noting the upstream kernel advisory from Greg Kroah-Hartman (Red Hat Bugzilla). SUSE and Debian issued security advisories and kernel update packages addressing this CVE among others. The Yocto Project security mailing list also flagged the issue for embedded Linux maintainers (Feedly Intelligence). Community reaction has been measured, consistent with a kernel WiFi subsystem fix that requires adjacent network access and lacks a public exploit.