CVE-2026-41281 Overview
CVE-2026-41281 affects the Android application あんしんフィルター for au provided by KDDI CORPORATION. The application transmits sensitive information in cleartext, which falls under Cleartext Transmission of Sensitive Information [CWE-319]. A network-positioned attacker performing a man-in-the-middle (MITM) attack can intercept and modify the unprotected communications. Successful exploitation can lead to information disclosure or tampering of data exchanged between the app and its backend services. The issue is reachable over the network without authentication and without user interaction.
Critical Impact
A man-in-the-middle attacker on the same network path can read and alter sensitive data transmitted by the app, enabling information disclosure and data tampering.
Affected Products
- Android App あんしんフィルター for au (KDDI CORPORATION)
Discovery Timeline
- 2026-05-14 - CVE-2026-41281 published to NVD
- 2026-05-14 - Last updated in NVD database
Technical Details for CVE-2026-41281
Vulnerability Analysis
The あんしんフィルター for au Android application transmits sensitive information over an unencrypted channel. Because traffic is not protected by Transport Layer Security (TLS), any attacker with the ability to observe or relay traffic between the device and the application backend can read the contents. The same positioning lets the attacker rewrite request and response data before delivery. The classification under [CWE-319] reflects the absence of confidentiality and integrity controls on the transport layer, not a flaw in cryptographic primitives.
Root Cause
The application uses cleartext network communication for traffic that should be protected. Android applications targeting modern API levels can still permit cleartext traffic when the network security configuration allows it or when the code explicitly issues plain http:// requests. The result is that sensitive fields traverse the network without confidentiality or integrity protection.
Attack Vector
An attacker requires a network position between the affected device and the application servers. Common scenarios include rogue Wi-Fi access points, ARP spoofing on shared LAN segments, malicious upstream networks, and compromised routers. Once positioned, the attacker passively captures sensitive fields or actively rewrites traffic to manipulate application behavior. No credentials or user interaction are required.
No verified proof-of-concept code is available. Refer to the JVN Security Advisory for vendor-supplied technical details.
Detection Methods for CVE-2026-41281
Indicators of Compromise
- Unexpected plaintext HTTP traffic originating from the あんしんフィルター for au application to KDDI-associated hosts.
- TLS downgrade events or repeated certificate failures correlated with sessions from the affected app.
- ARP table inconsistencies or gateway MAC address changes on networks where affected devices are active.
Detection Strategies
- Inspect mobile network telemetry for cleartext http:// requests from the affected package and flag any sensitive fields in those payloads.
- Correlate Wi-Fi association events with the appearance of unauthorized access points advertising the same SSIDs used by managed devices.
- Use mobile threat defense or network monitoring tools to identify MITM patterns such as SSL stripping and unsolicited proxy injection.
Monitoring Recommendations
- Continuously monitor egress traffic from managed mobile devices for unencrypted application protocols.
- Alert on connections from corporate or family-managed devices to untrusted networks while the affected app is active.
- Track JVN and KDDI advisory channels for updated builds and fixed version identifiers.
How to Mitigate CVE-2026-41281
Immediate Actions Required
- Update あんしんフィルター for au to the latest version available through Google Play once KDDI publishes a fixed release.
- Avoid using the application on untrusted networks, including public and open Wi-Fi, until the patched version is installed.
- Route managed-device traffic through a trusted VPN to add a transport-layer wrapper around any cleartext flows.
Patch Information
KDDI CORPORATION has published advisory information through the Japan Vulnerability Notes portal. See the JVN Security Advisory for the current fixed version and remediation guidance. No CPE or affected version range is enumerated in the NVD record at the time of publication.
Workarounds
- Restrict the affected app to networks under organizational control until a patched build is deployed.
- Enforce always-on VPN policies on managed Android devices to protect cleartext traffic in transit.
- Disable automatic connection to open Wi-Fi networks to reduce exposure to MITM positioning.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
