CVE-2025-20634

Remote code execution via unchecked modem input

Published Feb 3, 2025 · Updated Feb 17, 2026

Out-of-bounds write in MediaTek Modem NR16, NR17, and NR17R allows remote attackers to execute code through a rogue base station. The modem processes attacker-controlled cellular input without a required bounds check and writes beyond the intended buffer; MediaTek has not disclosed the specific handler or buffer. Exploitation requires the UE to connect to an attacker-controlled base station, but requires no privileges or user interaction and enables code execution.

CVSS severity8.8
High
EPSS probability0.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in MediaTek Modem NR16, NR17, and NR17R allows remote attackers to execute code through a rogue base station. The modem processes attacker-controlled cellular input without a required bounds check and writes beyond the intended buffer; MediaTek has not disclosed the specific handler or buffer. Exploitation requires the UE to connect to an attacker-controlled base station, but requires no privileges or user interaction and enables code execution.

The record

CVE
CVE-2025-20634
Published
Feb 3, 2025
Updated
Feb 17, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1203
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 3, 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

8.8CISA-ADPCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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-787Out-of-bounds Write
T1203Exploitation for Client Execution

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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