Critical severity · published Mar 5, 2026
CVE-2025-13476
Rakuten Viber uses broken or risky cryptographic Algorithm
9.8
CVSS
0.4%
EPSS
No
On KEV
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)
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 30% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RV
Rakuten Viber Cloak - Android · Rakuten Viber
25.7.2.0g before 27.2.0.0g · source: vendor
RV
Rakuten Viber Cloak - Windows · Rakuten Viber
v25.6.0.0 before v27.3.0.0 · source: vendor
VI
Viber · Rakuten
25.6.0 through 25.8.1.0; 9.3.0.6 · source: NVD