CVE-2025-20666

Device crash via uncaught modem exception

Published May 5, 2025 · Updated Feb 17, 2026

Reachable assertion in MediaTek Modem NR15 allows remote attackers controlling a rogue base station to crash a connected device. An uncaught exception in the modem's reachable assertion handling terminates the system when the base station supplies triggering input. Exploitation requires the UE to connect to the attacker-controlled base station; no privileges or user interaction are required, and the reported consequence is a system crash.

CVSS severity6.5
Medium
EPSS probability0.80%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in MediaTek Modem NR15 allows remote attackers controlling a rogue base station to crash a connected device. An uncaught exception in the modem's reachable assertion handling terminates the system when the base station supplies triggering input. Exploitation requires the UE to connect to the attacker-controlled base station; no privileges or user interaction are required, and the reported consequence is a system crash.

The record

CVE
CVE-2025-20666
Published
May 5, 2025
Updated
Feb 17, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-617, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 5, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 17, 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

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-617Reachable Assertion
T1499.004Application or System Exploitation

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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