CVE-2026-20401
Published: 02 February 2026
Summary
CVE-2026-20401 is a high-severity Reachable Assertion (CWE-617) vulnerability in Mediatek Nr15. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 35.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Requires detection and response to audit logging failures as an unusual or exceptional condition.
Implements detection of unusual or exceptional conditions followed by safe mode entry, reducing the window for exploitation of unchecked conditions.
Training ensures users perform required checks for unusual or exceptional conditions as part of contingency roles, limiting attacker leverage from skipped validations.
IR testing directly validates checks for unusual or exceptional conditions that could indicate security incidents.
Requires ongoing monitoring of organization-defined metrics and analysis, enabling checks for unusual or exceptional conditions.
Security testing routinely checks for unusual or exceptional inputs/conditions, identifying missing validation steps that flaw remediation then resolves.
Requires detection of unusual conditions followed by a controlled transition to the defined failure state.
MTTF determination forces explicit checks for conditions that precede predictable component failure.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vulnerability enables remote system crash via uncaught exception (reachable assertion) when connecting to rogue base station, directly matching application/system exploitation for endpoint DoS.
NVD Description
In Modem, there is a possible system crash due to an uncaught exception. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges…
more
needed. User interaction is not needed for exploitation. Patch ID: MOLY01738310; Issue ID: MSV-5933.
Deeper analysisAI
CVE-2026-20401 is a vulnerability in the Modem component that allows a possible system crash due to an uncaught exception. It affects devices incorporating vulnerable MediaTek modems, as detailed in the vendor's product security bulletin.
The vulnerability can be exploited remotely by an attacker who controls a rogue base station. When user equipment (UE) connects to the rogue base station, the uncaught exception triggers a system crash, resulting in a denial of service (DoS). Exploitation requires no additional execution privileges or user interaction. The CVSS v3.1 base score is 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), with associated weakness enumerations CWE-617 (Reachable Assertion) and CWE-754 (Improper Check for Unusual or Exceptional Conditions).
MediaTek's February 2026 product security bulletin at https://corp.mediatek.com/product-security-bulletin/February-2026 provides mitigation guidance, including patch MOLY01738310 for issue MSV-5933. Affected vendors and device manufacturers should apply this patch to remediate the vulnerability.
Details
- CWE(s)