CVE-2026-20408
Published: 02 February 2026
Summary
CVE-2026-20408 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Openwrt Openwrt. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 0.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-16 (Memory Protection).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Directly remediates the heap buffer overflow vulnerability in the wlan component by identifying, reporting, and applying the specified patch WCNCR00461651.
Implements memory protection mechanisms such as heap canaries, safe unlinking, or address space layout randomization to prevent exploitation of the out-of-bounds write in wlan.
Validates incoming wireless network inputs for proper length and syntax to block malformed packets that trigger the heap buffer overflow.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Heap buffer overflow (out-of-bounds write) in wlan component directly enables remote privilege escalation over adjacent network with no auth or user interaction.
NVD Description
In wlan, there is a possible out of bounds write due to a heap buffer overflow. This could lead to remote (proximal/adjacent) escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID:…
more
WCNCR00461651; Issue ID: MSV-4758.
Deeper analysisAI
CVE-2026-20408 is a heap buffer overflow vulnerability in the wlan component that enables an out-of-bounds write. Published on 2026-02-02, it is tracked under CWEs CWE-122 and CWE-787 and affects MediaTek products, with a CVSS v3.1 base score of 8.8 (AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
An unauthenticated attacker with adjacent (proximal) network access can exploit this vulnerability with low complexity and no user interaction required. Exploitation leads to remote escalation of privilege, granting high-impact access to confidentiality, integrity, and availability without additional execution privileges needed.
MediaTek's February 2026 product security bulletin at https://corp.mediatek.com/product-security-bulletin/February-2026 details mitigation, including patch WCNCR00461651 for issue MSV-4758. Security practitioners should apply this patch to vulnerable devices.
Details
- CWE(s)