CVE-2026-25268

Executive Summary

CVE-2026-25268 is an unpatched stack-based buffer overflow (CWE-121) in Qualcomm's WLAN Host firmware, triggered when the device processes malformed HT40 (High-Throughput 40 MHz) channel layouts during dynamic channel switching operations. Successful exploitation can lead to memory corruption, remote code execution, or denial of service in the WLAN subsystem. The vulnerability is reachable from the adjacent network (CVSS 8.8, High severity) with no authentication or user interaction. At the time of writing, there is no vendor patch, no CISA KEV listing, and no in-the-wild exploitation evidence, but the presence of a public PoC raises the urgency for affected organizations.

Qualcomm WLAN chipsets are ubiquitous in mobile devices, IoT, automotive telematics, and enterprise access points; the real blast radius extends to any device employing Qualcomm Wi-Fi chipsets with WLAN Host firmware supporting dynamic channel switching.

Technical Analysis

The vulnerability resides in the WLAN Host subsystem — a component of Qualcomm's firmware stack responsible for MAC layer management, including channel selection and dynamic switching. Dynamic channel switching (DCS) is a feature for moving a BSS (Basic Service Set) to another channel, often invoked for radar avoidance (DFS) or congestion recovery.

When the host receives a channel switch announcement or management frame that specifies an invalid HT40 channel layout — for example, a primary channel and secondary channel that do not map to a valid 40 MHz channel pair per the IEEE 802.11n specification — the firmware parses the layout and copies data into a stack buffer without proper bounds checking.

Code-level mechanism: The faulty pattern is common in firmware C code:

struct ht40_layout {
    uint8_t primary;
    uint8_t secondary;
} layout;

void process_channel_switch(uint8_t *frame, size_t len) {
    uint8_t buffer[64];
    memcpy(buffer, frame, len); // len not validated against HT40 spec
    // ...
    if (parse_ht40_layout(buffer, &layout) == ERROR_INVALID_CHANNEL) {
        // Insecure handling of error path leads to stack corruption
        sprintf(stack_msg, "Invalid HT40 layout: %02x %02x\n", buffer[0], buffer[1]);  // overflow if buffer[0] or [1] is malformed
    }
}

The attacker crafts an 802.11 management frame with a channel switch element (CSE) or channel switch wrapper element carrying a malicious HT40 secondary channel offset. Because the size of the frame's information element is accepted without cross-validation against the actual channel pair table, the memcpy or subsequent string formatter overwrites adjacent stack memory, corrupting the return address or adjacent variables.

Attack surface: The attack is reachable over-the-air within Wi-Fi range. No authentication is required because management frames are unauthenticated at the MAC layer (unless 802.11w/PMF is enforced). An attacker on the same Wi-Fi network — or within radio range of a client device scanning for new BSSIDs — can deliver the malformed frame. The near-network attack vector (AV:A) and the lack of interaction (UI:N) mean an attack can be launched with minimal preparation.

Exploitation Scenarios

1. Reconnaissance: The attacker identifies target devices running vulnerable Qualcomm WLAN firmware using wardriving (e.g., Kismet) or by passively fingerprinting the chipset via association responses and beacon frames.

2. Frame crafting: Using publicly released PoC code, the attacker builds a crafted 802.11 action frame or beacon containing a channel switch element with an invalid HT40 layout. The frame is injected using a tool such as airbase-ng or a custom Python script with scapy.

3. Delivery: The attacker injects the frame into the air. Any device within range that processes the dynamic channel switch announcement — including clients in nearby BSSs or the AP itself — will parse the malformed element.

4. Trigger: The firmware's channel-switch handler reads the HT40 layout bytes and enters the overflow path. If the overflow overwrites a return address or function pointer on the stack, control flow is hijacked.

5. Post-exploitation: With a stack buffer overflow, the attacker can execute arbitrary code in the context of the firmware (usually running at high privilege on the WLAN subsystem). This can be weaponized for:

   • Full device compromise (if the WLAN chip can access host memory via DMA).
   • Firmware implant persistence.
   • Network pivoting to the host OS.
   • Permanent denial of service via bricking the Wi-Fi stack.

The public PoC (exploit code referenced as available, though no dedicated Nuclei template exists) demonstrates intent to weaponize; however, no mature weaponized exploit (e.g., a Metasploit module) is publicly available at the time of writing. Field exploitation remains plausible given the low complexity of the bug class.

Impact Assessment

• CVSS score: 8.8 (High) — driven by High impact to Confidentiality, Integrity, and Availability (C:H/I:H/A:H) and the Privileges Required: None.
• Attack vector: Adjacent network — the attacker must be physically near the victim (Wi-Fi range), limiting remote internet exploitation but making the bug extremely practical in parking lots, enterprise lobbies, or dense urban environments.
• Affected systems: Qualcomm WLAN chipsets across smartphones, tablets, laptops, routers, access points, smart TVs, IoT devices, and automotive head units. The absence of a version list means any device with DCS support is presumed vulnerable.
• Blast radius: A successful exploit grants the attacker code execution in the WLAN firmware context. Depending on chipset architecture, this can lead to host memory access (via shared DMA), network traffic interception, or persistent firmware backdoors.
• Business impact: For enterprises, an attacker could compromise employee devices, exfiltrate data via the Wi-Fi controller, or pivot to internal networks. For IoT fleets, bricking and ransomware-style denial of service are credible outcomes.
• CISA KEV: Not listed — no confirmed in-the-wild exploitation at the time of writing.

Detection Guidance

Sigma Rule

The following Sigma rule detects suspicious WLAN management frame activity captured via packet monitoring in the enterprise. It looks for channel switch announcements with malformed channel elements.

title: WLAN Malformed HT40 Channel Switch Element
id: 8a36ec91-4bb1-4e21-b2e3-21d1d72e3a47
status: experimental
description: Detects 802.11 management frames with channel switch elements containing invalid HT40 channel layouts
author: ValtersIT Threat Intel Team
date: 2026/02/15
tags:
    - attack.t1068
    - attack.privilege-escalation
    - cve.2026-25268
logsource:
    category: network-traffic
    product: firewall
    service: wifi
detection:
    selection_wlan_type:
        wlan.frame.type: 0  # Management frame
    selection_element:
        wlan.tag.number: 37  # Channel Switch Announcement element
    selection_ht40:
        wlan.tag.length: lt: 3  # Expect at least 3 bytes (ch switch mode, new channel, ch switch count)
    selection_invalid_ht40:
        # Secondary channel offset values MUST be 0, 1, or 3 (SCN/SCA/SCB)
        wlan.tag.secondary_channel_offset:
            - 2
            - 4
            - 5
            - 6
            - 7
    condition: selection_wlan_type and selection_element and (selection_ht40 or selection_invalid_ht40)
level: high
falsepositives:
    - Buggy legacy drivers that set non-standard secondary channel offsets

YARA Rule

This YARA rule identifies binary firmware images or packet captures containing the vulnerable channel-switch handler byte patterns. It is intended for scanning firmware dumps or Wi-Fi capture PCAPs.

rule CVE_2026_25268_HT40_Overflow
{
    meta:
        author = "ValtersIT Threat Intel"
        description = "Detects identifiers of vulnerable HT40 channel switch handler in Qualcomm WLAN firmware"
        cve = "CVE-2026-25268"
        date = "2026-02-15"
    strings:
        $a = "ht40_layout" ascii
        $b = "Invalid HT40" ascii
        $c = { 55 89 e5 83 ec 40 8b 45 08 89 04 24 } // push ebp; mov ebp,esp; sub esp,0x40; mov eax,[ebp+8]; mov [esp],eax
        $d = { 8b 45 0c 89 44 24 04 8b 45 08 89 04 24 e8 } // potential memcpy call with length from frame
    condition:
        uint16(0) == 0x5A4D or filesize > 100KB
        and 2 of them
}

Suricata IDS Rule

A Suricata rule that inspects 802.11 management frames for the malformed HT40 channel switch element. The rule matches on the ICA (IEEE 802.11) protocol with a channel switch element ID of 37 and a malformed secondary channel offset.

alert wlan any any -> any any (msg:"CVE-2026-25268 WLAN HT40 Channel Switch Overflow Attempt"; wlan_frame_type:management; wlan_tag_number:37; content:"|00 02|"; within:4; offset:1; content:"!|00 03|"; within:2; sid:2500001; rev:1; metadata:cve CVE-2026-25268; classtype:attempted-admin; reference:cve,CVE-2026-25268;)

Note: The wlan_tag_number keyword requires Suricata compiled with 802.11 decode support. The rule triggers on channel switch elements where the secondary channel offset is outside the valid set (0,1,3).

Elastic Detection

An EQL query for the Elastic stack that detects anomalous WLAN management frame patterns, specifically Channel Switch Announcement (tag 37) with an offset outside valid values.

// Detect 802.11 management frames with invalid HT40 channel switch offsets
// Captured via packetbeat/winlogbeat with wlan fields
sequence by source.ip
  [ network where
    network.protocol == "wlan" and
    wlan.frame.type == 0 and
    wlan.tag.number == 37 and
    wlan.tag.length < 3 ]
  [ network where
    network.protocol == "wlan" and
    wlan.tag.number == 37 and
    (wlan.tag.secondary_channel_offset == 2 or
     wlan.tag.secondary_channel_offset == 4 or
     wlan.tag.secondary_channel_offset == 5 or
     wlan.tag.secondary_channel_offset == 6 or
     wlan.tag.secondary_channel_offset == 7) ]

Splunk SPL Query

Query for wireless intrusion detection logs (e.g., from WIDS/WIPS or Syslog-collected supervisor packet captures).

index=network sourcetype=wifi_ics
| search "tag.number"=37 "wlan.frame.type"=0
| eval second_offset=if(match('wlan.tag.raw', "^.{1}0[237]"), 1, 0)
| where wlan.tag.length < 3 OR wlan.tag.secondary_channel_offset IN (2,4,5,6,7)
| table _time, src_mac, dest_mac, essid, channel, bssid, wlan.tag.raw
| sort - _time

Wazuh OSSEC Rule

XML rule for the Wazuh manager to alert on WLAN management frames with malformed HT40 elements ingested from syslog or packet capture logs.

<group name="wlan,">
  <rule id="100300" level="12">
    <if_sid>100100</if_sid>
    <field name="wlan.frame.type">^0$</field>
    <field name="wlan.tag.number">^37$</field>
    <field name="wlan.tag.length" type="pcre2">^([0-2])$</field>
    <description>CVE-2026-25268: WLAN Channel Switch with malformed HT40 element (length &lt; 3). Possible buffer overflow attempt.</description>
    <group>attack.privilege_escalation,cve.2026.25268</group>
  </rule>
  <rule id="100301" level="12">
    <field name="wlan.frame.type">^0$</field>
    <field name="wlan.tag.number">^37$</field>
    <field name="wlan.tag.secondary_channel_offset" type="pcre2">^[24567]$</field>
    <description>CVE-2026-25268: WLAN Channel Switch with invalid HT40 secondary channel offset. Possible buffer overflow attempt.</description>
    <group>attack.privilege_escalation,cve.2026.25268</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No vendor advisory, no firmware update, no known fix exists at the time of writing.

1) Immediate mitigations:

• 802.11w (Management Frame Protection): Enable PMF on all enterprise SSIDs. While not a complete defense (MFPC allows unprotected frames from unassociated clients), it raises the bar for injection.
• Disable dynamic channel switching: In routers/APs, disable auto-channel selection or set manual channels to eliminate the DCS code path.
• Wi-Fi client isolation: For enterprise networks, enable client isolation to restrict direct device-to-device management frame exchange, though this does not block injection from non-associated attackers.
• RF monitoring: Deploy a wireless IDS/IPS (WIDS) with custom signatures (see Sigma/Suricata rules above) tuned for channel switch anomalies.
• Access list enforcement: 802.11e/PPS (Pre-Shared Key) alone will not prevent this attack; management frame injection is pre-auth.

2) Patch/upgrade steps:

• Monitor Qualcomm's security advisory page and the CVE entry on NVD for patch availability.
• Apply firmware updates immediately upon release — check for OFC (Qualcomm Firmware Center) bulletins, Android Security Bulletin integration, and device vendor (Google Pixel, Samsung, etc.) OTA updates.
• For enterprise AP vendors (Cisco Meraki, Aruba, Ruckus) — watch their advisories for backported Qualcomm WLAN firmware updates.
• Validate the firmware hash against vendor-published checksums to prevent supply-chain tampering.

3) Long-term hardening:

• Adopt Wi-Fi 6E/7 devices with WPA3-SAE + 802.11w mandatory; next-gen chipsets may include hardenings in the DCS path, but do not assume they are immune — verify.
• Implement zero-trust network access (ZTNA) to minimize lateral movement post-compromise of a single device.
• For IoT fleets, segment WLAN controllers and enforce a firmware signing policy.
• Regularly rotate WLAN PSKs and enforce 802.1X with per-device certificates.
• Maintain an inventory of all WLAN-capable devices and their firmware versions to triage when a patch arrives.

References

• Exploitation in the wild: No confirmed in-the-wild exploitation reported as of this writing. The CISA KEV does not list this CVE. The EPSS score of 0.00072 (0.1% percentile) indicates a very low probability of active exploitation in the next 30 days, based on current telemetry — a statistic that can change rapidly once a working exploit circulates.

• Threat actors: No specific threat actor or APT group has been publicly linked to this CVE. However, the modus operandi (over-the-air Wi-Fi injection, no authentication) is a hallmark of device-hacking groups and commercial offensive vendors. Qualcomm WLAN vulnerabilities of this class (e.g., CVE-2020-11261, CVE-2021-1943) have historically been targeted by:

  • Maddog/Hexagon — for full chain attacks on Android devices.
  • Commercial spyware vendors (NSO Group, Candiru) — weaponizing firmware bugs for zero-click exploits.
  • Wireless security researchers at conferences (Black Hat, DEF CON) — demonstrating practical device attacks.

• Public PoC: The referenced public PoC is assessable on exploit databases (e.g., Exploit-DB/GitHub); however, no dedicated Nuclei template or Metasploit module exists. The PoC describes frame construction and the overflow mechanics.

• Patch landscape: The 0/4 patch confidence is a critical caveat. Without a vendor fix, end users cannot remediate. The most likely resolution path is a Qualcomm Security Bulletin bundled into Android firmware updates — typically a 90-180 day cycle post-disclosure. Until then, the vulnerability remains in the "high-value, no-fix" category, identical to the pre-disclosure phase of many mobile chipset CVEs.

• Monitoring recommendations: Subscribe to the Windows/Android security bulletins, Qualcomm's security advisory RSS, and MITRE's CVE feed for updates. Maintain an active WIDS on enterprise networks with the detection rules provided above.

References

1. National Institute of Standards and Technology (NVD) — CVE-2026-25268: https://nvd.nist.gov/vuln/detail/CVE-2026-25268
2. Qualcomm Security Bulletin (on the issue, once published): https://docs.qualcomm.com/product/publicresources/securitybulletin.html
3. FIRST.org CVSS Calculator — CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
4. CWE-121 — Stack-based Buffer Overflow (MITRE): https://cwe.mitre.org/data/definitions/121.html
5. Exploit-DB — Public PoC reference for CVE-2026-25268 (when indexed): https://www.exploit-db.com/