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 34.2th 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-11 (Error Handling) and SI-2 (Flaw Remediation).
Deeper analysis
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.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-5149
Vulnerability details
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.
- CWE(s)
Related Threats
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.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly remediates the uncaught exception vulnerability by applying the vendor-provided patch MOLY01738310 to the MediaTek modem firmware.
Ensures the modem properly detects and handles exceptional conditions from rogue base stations, preventing system crashes due to CWE-617 and CWE-754 weaknesses.
Protects system availability against remote denial-of-service attacks triggered by malformed inputs from rogue base stations causing modem crashes.