CVE-2026-20452: MediaTek WLAN Driver Heap Buffer Overflow (CVSS 8.0)

Technical summary

CVE-2026-20452 is a heap buffer overflow (CWE-122) in the WLAN AP driver across multiple MediaTek chipsets. The vulnerability is triggered remotely over a local network (AV:A in the CVSS vector) by an adjacent attacker with low privileges (PR:L). No user interaction is required (UI:N). The flaw permits memory corruption that can lead to code execution within the User privilege context. The attack surface is limited to systems on the same network segment, reducing exposure compared to internet-facing vulnerabilities, though defense-in-depth remains important for isolated or trusted network environments.

Business impact

Devices running vulnerable MediaTek chipsets in enterprise or personal networks face compromise risk from insider threats or compromised peers. An attacker exploiting this flaw could monitor wireless communications, inject malicious traffic, or pivot to connected systems. For organizations deploying MediaTek-based network equipment (routers, access points, IoT gateways), this represents a local network integrity risk. Patching delays leave environments susceptible to lateral movement by network-adjacent adversaries. The impact scales with the number of deployed vulnerable devices and the sensitivity of the networks they serve.

Affected systems

MediaTek's dual-band and tri-band wireless chipsets across multiple generation lines are affected, including the MT6890, MT7615, MT7915, MT7916, MT7981, MT7986, MT7990, MT7992, and MT7993 families, along with their corresponding firmware images. These chipsets are commonly integrated into consumer routers, enterprise access points, and embedded networking devices. Organizations should audit procurement records and device inventories to identify affected hardware; many OEM deployments will require coordination with router or AP vendors for firmware availability, as MediaTek patches are often rolled into downstream OEM releases.

Exploitability

Exploitation requires network adjacency and low-level local user access, substantially limiting opportunistic attacks. An attacker must either be on the same subnet (or VLAN) or have already compromised a device with network access. The absence of authentication or user interaction requirements means that once an attacker meets the access prerequisites, the vulnerability is reliably exploitable. Public exploit code availability is not currently documented; however, heap corruption primitives are well-understood in security research, suggesting that functional exploits may emerge post-disclosure. The adjoining-network requirement makes this less critical than internet-facing flaws but high-priority for defense-in-depth strategies.

Remediation

Apply firmware updates referencing Patch ID WCNCR00480138 (Issue ID MSV-6295) as released by MediaTek and propagated through OEM vendors. Verify patch availability directly from your device manufacturer's support portal, as MediaTek patches often release first to OEMs who then distribute updated firmware. Until patching is complete, segment wireless networks to restrict access to trusted devices, enforce strong local authentication policies, and monitor for anomalous peer-to-peer traffic. Test patches in non-production environments before rollout to confirm device stability and feature compatibility.

Patch guidance

Contact your device manufacturer or OEM for availability of firmware incorporating Patch ID WCNCR00480138. MediaTek typically releases security fixes to partners rather than end-users directly. For standard consumer devices, check the manufacturer's firmware download page; for enterprise equipment, contact your vendor's technical support. Verify that any released firmware references Issue ID MSV-6295 or explicitly addresses CVE-2026-20452. Test the patch on representative equipment in your environment to ensure compatibility with existing configurations, VLANs, and management integrations before wide deployment. Maintain a rollback plan in case a patch causes unexpected behavior.

Detection guidance

Monitor wireless driver logs and system memory dumps for signs of buffer overflow attempts, though detection may be delayed or incomplete if corruption occurs in kernel space. Implement network segmentation and access control lists to restrict which devices can initiate proximity-based connections. Use intrusion detection or wireless intrusion prevention systems (WIPS) to detect anomalous network topology or unusual inter-device communications on your network. Maintain detailed firmware version inventories for all wireless devices so you can quickly confirm exposure after patches are released. Consider deploying endpoint detection and response (EDR) tools on systems connected to potentially vulnerable access points.

Why prioritize this

Despite requiring network adjacency and low privileges, this vulnerability merits HIGH priority (CVSS 8.0) due to the breadth of affected MediaTek chipsets and the potential for memory-corruption-based code execution. Wireless infrastructure is often overlooked in patch cadences, extending exposure windows. The lack of KEV notification suggests this is still in early disclosure, making rapid patching essential before active exploitation intensifies. Organizations with numerous deployed MediaTek devices should coordinate OEM outreach immediately to assess patch timelines.

Risk score, explained

The CVSS 3.1 score of 8.0 (HIGH) reflects a high-impact vulnerability (C:H/I:H/A:H) with substantial likelihood of exploitation once an attacker meets the proximity and privilege prerequisites. The adjacent-network vector (AV:A) and low-privilege requirement (PR:L) reduce the attack surface compared to unauthenticated remote attacks, but do not diminish the severity of the impact if exploitation succeeds. The lack of user interaction (UI:N) ensures reliable triggering. For organizations with strong network segmentation and access controls, residual risk may be lower; for flat networks or environments with high insider-threat risk, practical risk is elevated.

Frequently asked questions