CVE-2026-21117

Executive Summary

CVE-2026-21117 is an improper access control vulnerability in CocktailBarService, a system-level service on Samsung Android devices. The flaw allows local attackers to access sensitive information without requiring elevated privileges or user interaction. No public exploit, PoC, or patch is currently available, and the vulnerability remains unpatched as of the latest tracked sources. Organizations deploying Samsung mobile devices in enterprise environments should prioritize this issue due to the inherent trust placed in system services and the potential for information disclosure.

Technical Analysis

CocktailBarService is a Samsung-specific system service responsible for managing edge screen panels, notification interactions, and related UI components. The vulnerability is classified as improper access control (CWE-284), indicating that the service fails to properly enforce permission checks or access boundaries for local callers. This allows a malicious application installed on the device — or a local attacker with limited access — to invoke service methods or access data that should be restricted to privileged system components.

The NVD description states: "Improper access control in CocktailBarService prior to SMR Oct-2026 Release 1 allows local attackers to access sensitive information." No further technical detail is provided regarding specific methods, parameters, or data types exposed. The vulnerability is local in nature, requiring the attacker to have some level of access to the device (e.g., a malicious app with no special permissions, or a user-level process). It does not require user interaction and has low attack complexity, making it a reliable information disclosure vector once an attacker gains a foothold on the device.

The affected component is part of Samsung's One UI framework, which is not part of the Android Open Source Project (AOSP). Therefore, the vulnerability is specific to Samsung devices and not mitigated by standard Android security updates. The patch is expected via Samsung Monthly Rollup (SMR) Oct-2026 Release 1, but no evidence of a released patch exists in tracked sources.

Exploitation Scenarios

No public PoC or exploit code is available; the attack chain is inferred from the vulnerability class (improper access control).

1. Reconnaissance / Target Identification: The attacker identifies a Samsung device running One UI with an unpatched version of CocktailBarService. This can be done by enumerating installed packages or checking the build fingerprint for Samsung-specific components. No network scanning is required; the attacker must have local access (e.g., a malicious app installed from a third-party store or a sideloaded APK).

2. Triggering the Flaw: The malicious app binds to or invokes the exposed interface of CocktailBarService. Due to improper access control, the service does not validate the caller's identity or permissions, allowing the app to call methods or access data that are normally restricted to system-level processes. The exact method names and parameters are not disclosed in the NVD description, but the vulnerability class suggests a missing permission check (e.g., checkCallingPermission() or enforceCallingPermission()).

3. Payload / Execution Method: The attacker crafts an Android intent or Binder transaction to interact with the vulnerable service. Since no specific endpoints or parameters are known, the attack is at the class level: an unprivileged app sends a request to the service, which processes it without proper authorization. No exploit code is publicly available, and the attack does not rely on memory corruption or code injection.

4. Post-Exploitation Impact: Successful exploitation results in the disclosure of sensitive information stored or managed by CocktailBarService. This could include notification content, edge panel data, user preferences, or other UI-related metadata. The impact is confidentiality-only (CVSS: C:H/I:N/A:N), meaning no integrity or availability loss. However, the leaked data could be used for further reconnaissance, social engineering, or lateral movement within the device (e.g., accessing tokens or credentials cached by the service).

Impact Assessment

The vulnerability has a CVSS 3.1 base score of 6.5 (Medium) with vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N, based on the inferred vector. The attack requires local access (AV:L) and low privileges (PR:L), with no user interaction (UI:N). The confidentiality impact is high (C:H), while integrity and availability are unaffected (I:N/A:N). The scope is unchanged (S:U), meaning the vulnerability does not allow escaping the security context of the service.

Affected systems are Samsung mobile devices (smartphones and tablets) running One UI versions prior to the October 2026 SMR. Given Samsung's large enterprise and consumer footprint, the blast radius is significant, especially for organizations with BYOD policies or field workers using Samsung devices. The vulnerability does not affect AOSP-based devices from other manufacturers. The lack of a patch increases the risk window, and adversaries could incorporate this into multi-stage mobile malware campaigns targeting Samsung devices.

Detection Guidance

Sigma Rule

title: Suspicious Access to CocktailBarService
id: 8f3a2b1c-4d5e-6f7a-8b9c-0d1e2f3a4b5c
status: experimental
description: Detects attempts to bind to or invoke Samsung CocktailBarService from non-system applications
author: Threat Intelligence Team
date: 2026-10-15
logsource:
  product: android
  service: audit
detection:
  selection:
    event: "binder_transaction"
    service_name: "CocktailBarService"
    calling_uid|not: "1000"  # not system UID
  condition: selection
falsepositives:
  - Legitimate system applications with elevated privileges
level: medium
tags:
  - attack.t1204.002
  - cve.2026.21117

YARA Rule

rule CVE_2026_21117_CocktailBarService_Access
{
    meta:
        description = "Detects APK files attempting to access CocktailBarService without proper permissions"
        author = "Threat Intelligence Team"
        date = "2026-10-15"
        cve = "CVE-2026-21117"
    strings:
        $service = "CocktailBarService" ascii wide
        $binder = "android.os.Binder" ascii wide
        $intent = "android.content.Intent" ascii wide
    condition:
        uint32(0) == 0x504B0304 and  // ZIP/APK magic
        all of them
}

Suricata IDS Rule

alert tcp any any -> any any (msg:"CVE-2026-21117 - Potential CocktailBarService Access Attempt"; flow:to_server,established; content:"CocktailBarService"; nocase; classtype:attempted-recon; sid:1000001; rev:1;)

Note: This rule is a network-level heuristic; the vulnerability is local, so network detection is limited. It may trigger on traffic from malicious apps exfiltrating data accessed via the service.

Elastic Detection

process where event.type == "start" and process.name == "app_process" and
  process.args : "*CocktailBarService*" and
  not process.parent.name : ("system_server", "zygote")

Splunk SPL Query

index=android_logs sourcetype=logcat
| search "CocktailBarService" AND ("Permission Denial" OR "SecurityException" OR "access denied")
| stats count by host, user, _time
| where count > 5

Wazuh OSSEC Rule

<group name="android,">
  <rule id="100200" level="10">
    <decoded_as>json</decoded_as>
    <field name="service">CocktailBarService</field>
    <field name="caller_uid">^((?!1000).)*$</field>
    <description>CVE-2026-21117: Unauthorized access to CocktailBarService detected</description>
    <mitre>
      <id>T1204.002</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate Mitigations:

   • Restrict installation of applications from untrusted sources (disable "Unknown Sources").
   • Use Mobile Device Management (MDM) to enforce app allowlisting and block sideloaded APKs.
   • Monitor device logs for anomalous Binder transactions involving CocktailBarService.
   • Apply the latest available Samsung security updates even if they do not yet include the October 2026 SMR; other patches may reduce the attack surface.

2. Patch/Upgrade Steps:

   • Once Samsung releases SMR Oct-2026 Release 1, ensure all Samsung devices receive the update via OTA or MDM.
   • Verify the patch level in Settings > About Phone > Software Information > Android Security Patch Level.
   • For enterprise fleets, use Samsung Knox or other EMM solutions to push the update and confirm compliance.

3. Long-Term Hardening:

   • Implement a vulnerability management program that includes mobile OS and vendor-specific components.
   • Conduct regular security assessments of Samsung devices, focusing on exposed system services.
   • Enforce least privilege for apps and use runtime permission controls.
   • Enable Samsung Knox security features such as Real-time Kernel Protection (RKP) and Defex where available.

References

1. NVD Entry for CVE-2026-21117: https://nvd.nist.gov/vuln/detail/CVE-2026-21117
2. Samsung Mobile Security Updates: https://security.samsungmobile.com/securityUpdate.smsb
3. Samsung Monthly Rollup (SMR) Overview: https://security.samsungmobile.com/workScope.smsb
4. CWE-284: Improper Access Control: https://cwe.mitre.org/data/definitions/284.html
5. MITRE ATT&CK T1204.002: https://attack.mitre.org/techniques/T1204/002/

No known threat actor campaigns or exploit-in-the-wild evidence are available for this CVE. CISA KEV does not list this vulnerability.