Cyber Resilience

CVE-2026-20434

Memory Safety in Mediatek Lr12A

Memory Safety
Published
02 March 2026
Modified
02 March 2026
Patch / advisory
View advisory
CVSS Score v3.1 7.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0022 12th percentile
Risk Priority 54 floored blend · peak EPSS

Summary

CVE-2026-20434 is a high-severity Out-of-bounds Write (CWE-787) vulnerability in Mediatek Lr12A. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 12th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-20434 is an out-of-bounds write vulnerability (CWE-787) in the Modem component due to a missing bounds check. It affects MediaTek modem firmware, as detailed in the vendor's product security bulletin. Published on 2026-03-02, the issue carries a CVSS v3.1 base score of 7.5 (AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H) and is tracked under Patch ID MOLY00782946 and Issue ID MSV-4135.

Exploitation requires an attacker to control a rogue base station, with a user equipment (UE) connecting to it; user interaction is needed for the UE to connect. No additional execution privileges are required by the attacker. Successful exploitation could result in remote escalation of privilege, potentially allowing high confidentiality, integrity, and availability impacts.

MediaTek addresses the vulnerability with patch MOLY00782946. Additional mitigation details and affected products are outlined in the March 2026 product security bulletin at https://corp.mediatek.com/product-security-bulletin/March-2026.

EU & UK References

Vulnerability Data

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…

more

additional execution privileges needed. User interaction is needed for exploitation. Patch ID: MOLY00782946; Issue ID: MSV-4135.

CWE(s)
CWE-787

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1211 Exploitation for Stealth Stealth
Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-20039Same product: Mediatek Lr12A
CVE-2023-32840Same product: Mediatek Lr12A
CVE-2023-20819Same product: Mediatek Lr12A
CVE-2023-32886Same product: Mediatek Mt2735
CVE-2023-32874Same product: Mediatek Lr13
CVE-2023-32888Same product: Mediatek Mt2735
CVE-2025-20634Same product: Mediatek Mt2737
CVE-2024-20154Same product: Mediatek Lr12A
CVE-2024-20131Same product: Mediatek Mt2737
CVE-2024-20151Same product: Mediatek Mt2737

Affected Assets

mediatek
lr12a
all versions
mediatek
lr13
all versions
mediatek
nr15
all versions
mediatek
nr16
all versions
mediatek
nr17
all versions

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation (including fuzzing and bounds checks) finds out-of-bounds write flaws before deployment.

SA-15 Development Process, Standards, and Tools partial match

Requiring documented secure-development standards and tools can mandate bounds-checked coding practices that avoid the weakness.

SI-10 Information Input Validation partial match

Input validation can structurally reject or sanitize data that would otherwise trigger an out-of-bounds write.

SI-16 Memory Protection partial match

Memory-protection mechanisms limit the exploitability and blast radius of a successful out-of-bounds write.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure-development practices (static analysis, bounds checking, code review) are the primary means of preventing out-of-bounds writes.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover out-of-bounds write flaws so they can be remediated.

PR.PS-02 partial match
prevents

Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development and acceptance can detect and prevent out-of-bounds write defects.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates practices that prevent out-of-bounds writes.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify bounds-checking and safe memory handling.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture and engineering principles reduce the likelihood of buffer overflows.

A.8.28 Secure coding partial match
prevents

Secure coding directly addresses out-of-bounds writes through language choice and coding standards.

A.8.32 Change management partial match
prevents

Change management can enforce review gates that catch unsafe memory operations before deployment.

References