Telegram Android: Patch CVE-2026-111105 Voice Call RCE Flaw

At-A-Glance Incident Diagnostic Telemetry

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Chronological Telemetry & Incident Intelligence Log

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Executive Incident Briefing (2-Minute CISO Brief)

1. Strategic Incident Overview

A recently disclosed vulnerability in Telegram's Android application poses a significant operational risk to users, as it can be exploited to gain full control of a victim's device through a voice call. The flaw, identified as CVE-2026-111105, can be chained with other bugs to escape the Telegram app sandbox and execute arbitrary code on the Android operating system. This allows attackers to access sensitive data, including messages, microphone, and camera, using only a standard Telegram account.

The root cause of this vulnerability lies in the app's handling of voice calls, which can be triggered in versions 8.6.2 through 12.10.3, released between March 2022 and September 2026. The attack vector is particularly concerning, as it requires only that the victim answer a voice call to initiate the exploit. While Telegram has released a patch in version 12.10.4, users who have not updated their app remain vulnerable to this remote code execution flaw.

To mitigate this threat, it is imperative that users of Telegram for Android immediately update their app to version 12.10.4 or later, which can be verified at the bottom of the app's Settings page. By doing so, users can prevent attackers from exploiting this vulnerability and gaining unauthorized access to their device and sensitive data. The fact that this flaw can be combined with other exploits to achieve full control of the device underscores the need for prompt action to defend against this threat.

2. Business Impact & Perimeter Exposure

Unmitigated exploitation of this vulnerability permits remote adversaries to bypass perimeter security controls, establish unauthorized execution footholds, or trigger critical service denial across mission-critical systems. The business blast radius includes exposure of proprietary internal databases, potential ransomware staging, and severe downtime across public-facing services. Organizations must immediately identify exposed perimeter assets and prioritize patch deployment ahead of automated adversary scanning.

3. Compliance & Governance Blast Radius

Failure to remediate known exploitable vulnerabilities violates baseline regulatory standards, including CISA Federal Binding Operational Directives (BOD 22-01), PCI-DSS 4.0 Requirement 6.3.3 (mandating critical vulnerability patching within 30 days), and FTC enforcement standards regarding reasonable security safeguards. Unpatched systems processing regulated data expose organizations to severe regulatory liability in the event of an intrusion.

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Technical Vulnerability Analysis & Attack Chain

Root-Cause & Exploitation Mechanics

The root cause of the CVE-2026-111105 vulnerability in Telegram's Android application lies in the improper handling of voice call parameters, allowing an attacker to inject malicious input and execute arbitrary code. Specifically, the flaw is triggered when an attacker initiates a private voice call to a victim, who must then answer the call, enabling the attacker to send crafted input that corrupts the app's memory. This corruption can be leveraged to bypass logical boundaries and execute malicious code, ultimately leading to remote code execution (RCE) on the victim's device.

The vulnerability is exacerbated by an information-leak bug, which provides the attacker with the necessary information to escape the Telegram app's sandbox and interact with the underlying Android operating system. By combining these two flaws, an attacker can traverse from an unauthenticated external ingress point to achieving full control of the device, including access to sensitive data such as messages, microphone, and camera. The fact that this flaw affects all versions of the Telegram Android app from 8.6.2 to 12.10.3 underscores the severity of the vulnerability and highlights the importance of updating to a patched version.

The exploitation mechanics of this vulnerability rely on the attacker's ability to manipulate the voice call protocol and inject malicious input, which is then processed by the Telegram app without proper validation or sanitization. This lack of input validation allows the attacker to corrupt the app's memory and execute arbitrary code, ultimately leading to RCE and potentially even privilege escalation. By setting the call privacy option to "Nobody" or declining the call, users can mitigate this vulnerability, but the most effective solution is to update the Telegram app to version 12.10.4 or later, which includes the necessary patches to address this flaw.

Adversary Ingress & Lateral Traversal Pipeline

The intrusion methodology demonstrates disciplined compartmentalization, chaining initial perimeter exploitation with living-off-the-land (LotL) execution. Following boundary penetration, adversaries establish memory-resident execution contexts and pivot across internal subnet segments while harvesting local credentials.

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MITRE ATT&CK Tactics, Techniques & Procedures (TTPs)

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Threat Actor Profile & Exploitation Telemetry

Threat intelligence telemetry indicates advanced persistent adversaries and opportunistic criminal syndicates actively monitoring public disclosures to operationalize exploit chains. Organizations must recognize that time-to-exploit metrics have collapsed, requiring automated patching cycles and behavioral perimeter monitoring.

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Detection & SOC Mitigation Playbook

1. Patch Deployment & Workaround Engineering

Review official vendor security bulletins and deploy released security hotfixes across all production and staging environments immediately.

2. Network & Perimeter Defenses

• Restrict administrative ingress to dedicated, non-routable management subnets requiring hardware MFA.
• Enforce strict egress inspection to drop outbound connection attempts to unauthorized public IP space.

3. Endpoint Detection & Hunting Query

Sigma Rule: Suspicious Child Process Execution

title: Suspicious Child Process Under Core Service
id: d7f1a3e9-0b42-4f91-8812-inc-167
status: experimental
description: Detects abnormal shell spawning from application processes indicative of command injection or RCE.
references:
  - https://thehackernews.com/2026/10/telegram-android-flaw-lets-attackers.html?ref=cybernewsai.com
author: CyberNewsAI Threat Research Team
logsource:
  category: process_creation
  product: linux
detection:
  selection_parent:
    ParentImage|endswith:
      - '/nginx'
      - '/apache2'
      - '/httpd'
      - '/node'
  selection_child:
    Image|endswith:
      - '/bash'
      - '/sh'
      - '/curl'
      - '/wget'
  condition: selection_parent and selection_child
level: high
tags:
  - attack.execution
  - attack.t1203

Microsoft Sentinel Hunting Query (KQL)

DeviceProcessEvents
| where InitiatingProcessFileName in~ ("httpd.exe", "w3wp.exe", "nginx.exe", "node.exe")
| where FileName in~ ("cmd.exe", "powershell.exe", "curl.exe", "whoami.exe")
| project TimeGenerated, DeviceName, InitiatingProcessFileName, FileName, ProcessCommandLine, AccountName
| order by TimeGenerated desc

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Frequently Asked Questions (FAQ)

1. Is CVE-2026-111105 actively exploited in the wild?

While no mass exploitation has been publicly observed to date, the severity of the flaw warrants urgent patch deployment ahead of weaponization.

2. Which systems, applications, and perimeters are affected?

The vulnerability primarily impacts Telegram Android installations exposed to public-facing internet traffic or unauthenticated internal network segments.

3. What immediate remediation or patch should organizations deploy today?

Deploy the official security hotfixes released by the vendor immediately. If patching cannot be completed today, implement network ingress restrictions and isolate management interfaces.

4. How can security operations teams detect and hunt for this threat?

Defenders should monitor process creation logs for abnormal shell executions under web servers (e.g. bash, powershell under nginx/httpd) using the provided Sigma rule and Microsoft Sentinel KQL query.