How to fix CVE-2025-13476?

Within 24 hours: Inventory all Rakuten Viber deployments across Android (v25.7.2.0g) and Windows (v25.6.0.0–v25.8.1.0) devices; disable Cloak mode feature organization-wide via Mobile Device Management (MDM) or endpoint management policies and communicate restriction to users. Within 7 days: Conduct audit of any communications relying on Cloak mode for security; evaluate alternative circumvention or privacy tools if needed for business operations. Within 30 days: Monitor Rakuten security advisories for patch release; establish process for rapid deployment once available; consider organizational policy on use of Viber for sensitive communications pending remediation.

Is Windows affected by CVE-2025-13476?

Rakuten Viber's Cloak mode (privacy/circumvention feature) on Android and Windows devices contains a critical flaw that allows network monitoring systems to identify and block Viber traffic despite users' expectation of anonymity.

CVE-2025-13476

CRITICAL

2026-03-05 [email protected]

9.8

CVSS 3.1

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 22:06 vuln.today

CVE Published

Mar 05, 2026 - 19:15 nvd

CRITICAL 9.8

Description

Rakuten Viber Cloak mode in Android v25.7.2.0g and Windows v25.6.0.0-v25.8.1.0 uses a static and predictable TLS ClientHello fingerprint lacking extension diversity, allowing Deep Packet Inspection (DPI) systems to trivially identify and block proxy traffic, undermining censorship circumvention. (CWE-327)

Analysis

Static TLS fingerprint in Rakuten Viber Cloak mode enables tracking despite privacy mode.

Technical Context

CWE-327 predictable TLS ClientHello.

Affected Products

['Rakuten Viber Android/Windows']

Remediation

Update Viber.

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +0.0

CVSS: +49

POC: 0

CVE-2025-13476 vulnerability details – vuln.today

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CVE-2025-13476

CVSS Vector

Lifecycle Timeline

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Description

Analysis

Technical Context

Affected Products

Remediation

Priority Score

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CVE-2025-13476

CVSS Vector

Lifecycle Timeline

Tags

Description

Analysis

Technical Context

Affected Products

Remediation

Priority Score

Share

External POC / Exploit Code