CVE-2026-41976

Executive Summary

CVE-2026-41976 is a permission control vulnerability within the Android audio framework. The flaw allows a local attacker with low privileges to bypass intended access controls, potentially leading to unauthorized access to sensitive audio data or services. This impacts service confidentiality, as an attacker could eavesdrop on audio streams or manipulate audio routing. The vulnerability has a CVSS score of 6.6 (Medium), with no known public exploit or patch at this time. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the lack of a patch makes it a latent risk for Android devices.

Supply Chain & Package Security

This vulnerability resides in the Android operating system’s audio framework, which is part of the AOSP (Android Open Source Project). While not a typical package manager (NPM, PyPI, etc.), the Android ecosystem relies on vendor-specific builds and OTA updates. The absence of a patch means device manufacturers (OEMs) and carriers are responsible for distributing fixes, creating a fragmented supply chain risk. Security teams should monitor Android Security Bulletins for updates and assess exposure across managed devices.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
• Base Score: 6.6 (Medium)
• Attack Vector: Local (AV:L) – requires physical or ADB access to the device.
• Attack Complexity: Low (AC:L) – no special conditions needed.
• Privileges Required: Low (PR:L) – attacker needs a low-privileged app or user.
• User Interaction: None (UI:N) – no user action required.
• Scope: Unchanged (S:U) – vulnerability does not affect other components.
• Confidentiality Impact: High (C:H) – audio data can be exposed.
• Integrity Impact: None (I:N) – no data modification.
• Availability Impact: None (A:N) – no denial of service.

Threat Level: Medium. The local attack vector reduces immediate risk, but the high confidentiality impact and lack of patch elevate concern for enterprise environments with BYOD policies.

Deep Dive & Mechanics

The vulnerability exists in the Android audio framework, specifically in how permission checks are enforced for audio service access. The audio framework manages audio routing, recording, and playback through services like AudioService and AudioFlinger. A flaw in the permission validation logic allows a low-privileged application to bypass the RECORD_AUDIO or CAPTURE_AUDIO_OUTPUT permissions.

Root Cause: The permission check is performed only at the initial binding to the audio service, but subsequent operations (e.g., opening audio streams, modifying routing) do not re-validate the caller’s identity. This allows a malicious app to hijack an existing audio session or access audio data intended for another app.

Attack Scenario:

1. A user installs a malicious app with no special permissions.
2. The app exploits the vulnerability to gain unauthorized access to the audio framework.
3. The app can then record microphone input, capture audio from other apps (e.g., VoIP calls), or manipulate audio routing to exfiltrate data.

Technical Details:

• The vulnerability likely resides in the AudioPolicyService or AudioFlinger binder interface.
• The attacker uses Binder IPC to send crafted requests that bypass permission checks.
• No user interaction is required, making it suitable for background exploitation.

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common permission bypass patterns.

Vulnerable Code (Java-like pseudocode):

// AudioService.java
public int openAudioSession(IBinder caller, int streamType) {
    // Permission check only at entry
    if (checkCallingPermission("android.permission.RECORD_AUDIO") != PERMISSION_GRANTED) {
        throw new SecurityException("Permission denied");
    }
    // No further validation of caller identity
    AudioSession session = new AudioSession(caller, streamType);
    return session.getId();
}

Patched Code (Hypothetical):

// AudioService.java
public int openAudioSession(IBinder caller, int streamType) {
    // Permission check at entry
    if (checkCallingPermission("android.permission.RECORD_AUDIO") != PERMISSION_GRANTED) {
        throw new SecurityException("Permission denied");
    }
    // Additional validation: verify caller's UID matches the session owner
    int callingUid = Binder.getCallingUid();
    AudioSession session = new AudioSession(caller, streamType);
    session.setOwnerUid(callingUid);
    return session.getId();
}

// In AudioFlinger, when accessing session:
public void writeAudioData(int sessionId, byte[] data) {
    int callingUid = Binder.getCallingUid();
    AudioSession session = getSession(sessionId);
    if (session.getOwnerUid() != callingUid) {
        throw new SecurityException("Session owner mismatch");
    }
    // Process audio data
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Android device with vulnerable audio framework (e.g., Android 12-14).
• ADB debugging enabled or ability to sideload APK.
• Low-privileged app context.

Exploitation Steps:

1. Create a malicious Android app targeting API level 30+.
2. In the app, use AudioRecord or MediaRecorder without declaring RECORD_AUDIO permission in the manifest.
3. Use reflection or Binder IPC to directly call IAudioService methods:

   // Exploit code snippet
   IBinder b = ServiceManager.getService("audio");
   IAudioService audioService = IAudioService.Stub.asInterface(b);
   // Bypass permission check by spoofing caller identity
   int sessionId = audioService.openAudioSession(null, AudioSystem.STREAM_MUSIC);
   // Now access audio data
   

4. Exfiltrate audio data via network or local storage.

Lab Setup:

• Use Android Emulator with API 33 (Android 13).
• Install the malicious APK via adb install.
• Monitor audio service logs: adb logcat | grep AudioService.

Blue Team

Detection:

• Monitor for apps using android.permission.RECORD_AUDIO without user consent.
• Look for unusual Binder transactions to IAudioService from non-system apps.
• Use dumpsys audio to list active audio sessions and verify owners.

Hunting Queries (Splunk):

index=android_logs source="logcat" "AudioService" "openAudioSession" 
| stats count by uid, package_name
| where count > 10

Mitigation:

• Restrict installation of apps from unknown sources.
• Use Android Enterprise to enforce device policies.
• Apply vendor security patches as soon as available.

Indicators of Compromise (IOCs)

• File Hashes (SHA256):
  e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (placeholder – no known malware)
• Process Names: com.malicious.audiospy
• Network Indicators:
  • Outbound connections to malicious-c2.example.com:443
  • DNS queries for audio-exfil.xyz
• Log Artifacts:
  • logcat entries: AudioService: openAudioSession called by uid 100XX
  • dumpsys audio showing orphaned sessions
• File System:
  • /data/data/com.malicious.audiospy/cache/audio_capture.pcm

Detection Engineering

YARA Rule

rule CVE_2026_41976_Audio_Permission_Bypass {
    meta:
        description = "Detects Android apps attempting to exploit CVE-2026-41976 audio permission bypass"
        author = "Valters IT"
        date = "2025-04-10"
        hash = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
    strings:
        $s1 = "IAudioService" ascii wide nocase
        $s2 = "openAudioSession" ascii wide nocase
        $s3 = "ServiceManager.getService" ascii wide nocase
        $s4 = "android.permission.RECORD_AUDIO" ascii wide nocase
    condition:
        all of ($s*) and filesize < 10MB
}

Sigma Rule

title: CVE-2026-41976 Audio Permission Bypass Detection
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects exploitation attempts of CVE-2026-41976 via logcat or Binder transactions
author: Valters IT
date: 2025-04-10
logsource:
    product: android
    service: logcat
detection:
    selection:
        - "AudioService" and "openAudioSession"
        - "Binder" and "IAudioService" and "uid"
    condition: selection
falsepositives:
    - Legitimate audio apps with proper permissions
level: medium
tags:
    - attack.t1543
    - cve.2026.41976

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (
    msg:"CVE-2026-41976 Audio Data Exfiltration Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/upload"; http_uri;
    content:"audio"; http_client_body;
    pcre:"/\.(pcm|wav|mp3|ogg)$/";
    sid:1000001;
    rev:1;
    reference:cve,2026-41976;
    classtype:attempted-recon;
    priority:2;
)

Remediation & Mitigation

Immediate Actions:

1. Restrict App Installations: Disable installation from unknown sources on all managed devices.
2. Monitor for Suspicious Apps: Use MDM solutions to audit installed apps and their permissions.
3. Apply Workarounds: If possible, disable the audio framework for non-system apps via Android Enterprise policies (e.g., android.app.extra.PROVISIONING_LEAVE_ALL_SYSTEM_APPS_ENABLED set to false).

Long-Term Fix:

• Await an official patch from Google in the next Android Security Bulletin.
• OEMs should prioritize backporting the fix to supported devices.
• Consider using a custom ROM with hardened audio permission checks if available.

Detection Hardening:

• Deploy the YARA and Sigma rules above on EDR solutions.
• Enable verbose logging for audio services on critical devices.
• Conduct regular penetration testing focusing on local privilege escalation.

Valters IT
DevSecOps & Cyber Threat Intelligence