CVE-2026-20406

UE crash via uncaught modem exception

Published Feb 2, 2026 · Updated Feb 2, 2026

Denial of service in MediaTek chipset modem firmware NR15, NR16, NR17, and NR17R allows remote attackers to crash a connected UE. The modem reaches an uncaught exception after processing input from a rogue base station; MediaTek has not disclosed the specific handler or exceptional condition. Exploitation requires connection to an attacker-controlled rogue base station; no privileges or user interaction are required, and impact is limited to a system crash.

CVSS severity6.5
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in MediaTek chipset modem firmware NR15, NR16, NR17, and NR17R allows remote attackers to crash a connected UE. The modem reaches an uncaught exception after processing input from a rogue base station; MediaTek has not disclosed the specific handler or exceptional condition. Exploitation requires connection to an attacker-controlled rogue base station; no privileges or user interaction are required, and impact is limited to a system crash.

The record

CVE
CVE-2026-20406
Published
Feb 2, 2026
Updated
Feb 2, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-770, CWE-754, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-754Improper Check for Unusual or Exceptional Conditions
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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