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Mediatek Chipset EUVDEUVD-2026-19568

| CVE-2026-20433 HIGH
Out-of-bounds Write (CWE-787)
2026-04-07 MediaTek
8.8
CVSS 3.1 · NVD
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Set up rogue base station
  2. Delivery
    UE connects to malicious network
  3. Exploit
    Send crafted modem protocol message
  4. Execution
    Trigger out-of-bounds write in modem parser
  5. Impact
    Escalate privilege to system level

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, write limits
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

UE must connect to attacker-controlled rogue base station. Exploitation occurs through malicious modem protocol messages during connection establishment. No authentication or special user privileges required, but physical proximity or cellular network control needed for rogue base station operation.

Impact

Real-world exploitation risk is moderate despite the 8.8 CVSS score. The CVSS vector CVSS:3.1/AV:A/AC:L/PR:N/UI:N indicates unauthenticated adjacent network access with low complexity, but the SSVC framework contextualizes this: exploitation status is 'none', not automatable, yet yields total technical impact (arbitrary code execution in modem context). The 0.06% EPSS score (18th percentile) reflects significant practical barriers-attackers must deploy specialized Software-Defined Radio (SDR) equipment costing thousands of dollars, position it within cellular range of targets, configure it to impersonate legitimate carriers, and induce victim devices to camp on the rogue base station. No public exploit code exists and no confirmed active exploitation (CISA KEV) at time of analysis. However, nation-state actors and advanced persistent threat groups have demonstrated rogue base station capabilities (IMSI catchers, Stingrays). The widespread deployment across 63 chipset variants in consumer smartphones, tablets, and IoT devices creates a large attack surface. Organizations in high-threat environments (government, critical infrastructure, defense contractors) should prioritize patching due to the privilege escalation outcome and difficulty of detection. For general enterprise deployments, the specialized attack requirements and low EPSS probability suggest medium priority behind actively exploited vulnerabilities.

Exploit ScenarioDerived

An attacker deploys a Software-Defined Radio (SDR) configured as a rogue LTE or 5G base station near a target location such as a corporate campus, government facility, or public venue. The rogue base station advertises stronger signal strength than legitimate carriers, causing nearby MediaTek-equipped smartphones to perform cell selection and camp on the attacker's infrastructure. Once the victim device establishes a connection, the attacker sends specially crafted cellular protocol messages (potentially in

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 07, 2026

Out-of-bounds write in MediaTek modem firmware enables remote privilege escalation when devices connect to attacker-controlled rogue cellular base stations. The vulnerability affects over 60 MediaTek chipset models widely deployed in smartphones and IoT devices, exploitable by adjacent network attackers without authentication (CVSS:3.1 AV:A/PR:N). While EPSS scores this at only 6% exploitation probability (18th percentile) and no active exploitation is confirmed at time of analysis, the attack s

Earlier versions of this analysis (1)
v1 Apr 07, 2026 - 03:45 CVSS 8.8

Out-of-bounds write in MediaTek modem firmware enables remote privilege escalation when devices connect to attacker-controlled rogue cellular base stations. The vulnerability affects over 60 MediaTek chipset models widely deployed in smartphones and IoT devices, exploitable by adjacent network attackers without authentication (CVSS:3.1 AV:A/PR:N). While EPSS scores this at only 6% exploitation probability (18th percentile) and no active exploitation is confirmed at time of analysis, the attack scenario requires specialized radio equipment and victim proximity to malicious infrastructure. Patch ID MOLY01088681 addresses the missing bounds check in modem baseband code.

RemediationAI

MediaTek released firmware patch MOLY01088681 addressing the modem bounds check vulnerability, documented in their April 2026 Product Security Bulletin at https://corp.mediatek.com/product-security-bulletin/April-2026. End users cannot directly apply MediaTek patches; device manufacturers (Samsung, Xiaomi, Oppo, Vivo, Realme, and others) must integrate the modem firmware fix into OEM-specific system updates. Users should immediately check for and install the latest security updates from their device manufacturer, prioritizing devices used in sensitive environments. OEMs should expedite integration of MOLY01088681 into monthly security maintenance releases. For enterprise deployments, Mobile Device Management (MDM) administrators should enforce automatic security updates and verify patch deployment across managed device fleets. As a partial mitigation until patches deploy, organizations can implement network policies restricting device roaming in high-risk geographic areas, though this does not prevent determined attackers with portable rogue base stations. Security teams should monitor for anomalous cellular behavior including unexpected base station connections, signal strength anomalies, or devices repeatedly losing and re-establishing network registration, though sophisticated attacks may not produce detectable signatures.

Affected VersionsENISA

MediaTek chipset MT6833
MediaTek chipset MT6983
MediaTek chipset MT6896
MediaTek chipset MT6895
MediaTek chipset MT6989
MediaTek chipset MT6893
MediaTek chipset MT6990
MediaTek chipset MT8792
MediaTek chipset MT6853
MediaTek chipset MT8863
MediaTek chipset MT2737
MediaTek chipset MT6875
MediaTek chipset MT6897
MediaTek chipset MT6877TT
MediaTek chipset MT6980
MediaTek chipset MT6879
MediaTek chipset MT8673
MediaTek chipset MT6980D
MediaTek chipset MT6895TT
MediaTek chipset MT6899
MediaTek chipset MT6835T
MediaTek chipset MT6877
MediaTek chipset MT8678
MediaTek chipset MT6983T
MediaTek chipset MT6890
MediaTek chipset MT8791T
MediaTek chipset MT8775
MediaTek chipset MT6855
MediaTek chipset MT6813
MediaTek chipset MT6855T
MediaTek chipset MT6989T
MediaTek chipset MT6891
MediaTek chipset MT8668
MediaTek chipset MT8791
MediaTek chipset MT6877T
MediaTek chipset MT6985T
MediaTek chipset MT6889
MediaTek chipset MT6991
MediaTek chipset MT8883
MediaTek chipset MT6853T
MediaTek chipset MT8771
MediaTek chipset MT6985
MediaTek chipset MT6880
MediaTek chipset MT6878
MediaTek chipset MT8793
MediaTek chipset MT6886
MediaTek chipset MT8675
MediaTek chipset MT6873
MediaTek chipset MT6833P
MediaTek chipset MT6835
MediaTek chipset MT6875T
MediaTek chipset MT6883
MediaTek chipset MT2735
MediaTek chipset MT8676
MediaTek chipset MT8798
MediaTek chipset MT8797
MediaTek chipset MT8893
MediaTek chipset MT6885
MediaTek chipset MT8795T
MediaTek chipset MT8755
MediaTek chipset MT8873
MediaTek chipset MT6878M

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability resides in the MediaTek modem baseband processor firmware, specifically in code handling cellular network communications. The root cause is CWE-787 (Out-of-bounds Write), where the modem fails to validate buffer boundaries when processing data from cellular base stations. MediaTek chipsets integrate modem, application processor, and connectivity functions on a single SoC; the affected modem component operates at high privilege levels with direct hardware access. The vulnerability spans 63 distinct chipset models including flagship (MT6989, MT6990, MT6991), mid-range (MT6833, MT6877, MT6985), and specialized IoT variants (MT2735, MT2737, MT8668-MT8893 series). The CVSS vector AV:A (Adjacent Network) reflects the cellular radio attack surface, requiring the attacker to operate a rogue base station within radio range of victim devices. The missing bounds check allows malicious Over-The-Air (OTA) cellular protocol messages to write beyond allocated memory buffers during protocol stack processing, potentially corrupting modem firmware memory structures.

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Severity by source

NVD PRIMARY 8.8 HIGH
AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

In Modem, there is a possible out of bounds write due to a missing bounds check. This could lead to remote escalation of privilege, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is needed for exploitation. Patch ID: MOLY01088681; Issue ID: MSV-4460.

Executive ViewAI

Why It Matters

CVE-2026-20433 is a high-severity remote privilege escalation affecting over 60 MediaTek chipset models in smartphones and IoT devices through out-of-bounds memory writes when connecting to rogue cellular base stations. This vulnerability poses significant risk to device security and data confidentiality across a broad installed base, though exploitation requires adjacent network positioning and specialized radio equipment, limiting immediate threat scope.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations include network segmentation to isolate critical devices from untrusted cellular connections where feasible; mobile device management (MDM) policies restricting automatic connection to unfamiliar networks; carrier-level monitoring for suspicious base station activity; and consideration of temporary restrictions on sensitive transactions on affected devices in high-threat environments pending patch availability.

Threat Intelligence Overview

EPSS Score
0.1%
Top 82% exploitable
Social Media
1
Sightings
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.1%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Controlled
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

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