CVE-2026-20470 Overview
CVE-2026-20470 is an information disclosure vulnerability in the MediaTek Telephony component. The flaw stems from a missing permission check [CWE-926], allowing a local attacker to access sensitive telephony data without additional execution privileges. Exploitation does not require user interaction. MediaTek tracks the fix as Patch ID ALPS11086431 and Issue ID MSV-8189, addressed in the August 2026 Product Security Bulletin.
Critical Impact
A locally installed application can read sensitive telephony data without holding the required permissions, resulting in confidentiality loss on affected MediaTek-based Android devices.
Affected Products
- MediaTek chipset-based devices running the affected Telephony component
- Android platform builds shipping the vulnerable MediaTek Telephony module
- Devices without the August 2026 MediaTek security patch level applied
Discovery Timeline
- 2026-08-03 - CVE-2026-20470 published to NVD
- 2026-08-03 - Last updated in NVD database
- August 2026 - MediaTek releases patch via Product Security Bulletin
Technical Details for CVE-2026-20470
Vulnerability Analysis
The vulnerability resides in the MediaTek Telephony component on Android. A code path exposes telephony data without verifying that the calling application holds the required permission. Because the permission check is missing entirely rather than incorrectly enforced, any local process on the device can invoke the affected interface and receive sensitive information back.
The weakness is classified as improper export of Android application components [CWE-926]. Attackers do not need to bypass authentication, escalate privileges, or trick a user into interacting with a malicious UI. A background application with no declared permissions is sufficient to trigger the disclosure.
The scope is limited to information disclosure. Integrity and availability of the device are not directly impacted, but the leaked telephony data can support follow-on attacks such as user tracking, SIM identification, or reconnaissance for targeted intrusions.
Root Cause
The root cause is an absent authorization check on an interface within the Telephony component. Developers exposed functionality that returns sensitive data but did not gate the call with a checkCallingPermission or equivalent enforcement step. Any caller reaching the endpoint receives data intended for privileged system components only.
Attack Vector
Exploitation requires local access, typically in the form of a malicious or compromised application already installed on the device. The attacking app queries the exposed Telephony interface and reads the returned data. No user interaction, prompt, or additional privilege grant is required during the attack.
No public proof-of-concept exploit is available at this time. See the MediaTek Product Security Bulletin for technical acknowledgment details.
Detection Methods for CVE-2026-20470
Indicators of Compromise
- Unprivileged applications making unexpected calls into Telephony service interfaces
- Third-party apps reading telephony identifiers without holding READ_PHONE_STATE or related permissions
- Anomalous binder IPC traffic targeting MediaTek Telephony service endpoints
Detection Strategies
- Audit installed applications for permission-to-behavior mismatches, focusing on apps that access telephony data without declared permissions
- Review Android logcat and system telemetry for calls to the affected Telephony interfaces from non-system UIDs
- Use mobile threat defense tooling to flag apps that repeatedly probe telephony service methods
Monitoring Recommendations
- Track the MediaTek security patch level (ro.vendor.build.security_patch) across the fleet and alert on devices below the August 2026 level
- Monitor enterprise MDM inventory for devices running vulnerable MediaTek chipsets pending patch rollout
- Correlate application install events with subsequent access to telephony APIs to identify suspicious behavior chains
How to Mitigate CVE-2026-20470
Immediate Actions Required
- Apply the August 2026 MediaTek security patch level or later on all affected devices
- Inventory MediaTek-based endpoints in the environment and prioritize patch deployment for devices handling sensitive communications
- Restrict sideloading and enforce installation only from vetted application sources through MDM policy
Patch Information
MediaTek addresses the issue under Patch ID ALPS11086431 (Issue ID MSV-8189). The fix is distributed through device OEMs as part of the August 2026 Android security patch level. Consult the MediaTek Product Security Bulletin and the device vendor's firmware release notes for availability on specific models.
Workarounds
- Remove untrusted third-party applications, particularly those requesting broad access unrelated to their stated function
- Enforce enterprise app allowlisting through MDM until the vendor patch is available for the device model
- Disable installation from unknown sources on managed devices to reduce the likelihood of a malicious local app being deployed
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
