CVE-2025-13476: Rakuten Viber Cloak – Android · Weak Cryptography
Affects Rakuten Viber Cloak – AndroidSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical : upgrade to 27.2.0.0g as a priority.
Data as of 29 Oct 2026, 19:04 UTC
Contested
Critical score, yet low EPSS after six months- EPSS
- 0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 27.2.0.0g, 27.3.0.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 5 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade Rakuten Viber Cloak to 27.2.0.0g (Android) or 27.3.0.0 (Windows).
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Rakuten ViberRakuten Viber Cloak - Android | Affected
| Fixed in
|
| Rakuten ViberRakuten Viber Cloak - Windows | Affected
| Fixed in
|
AI-suggested
1. 2. If you cannot patch yet, users should consider disabling Viber Cloak mode to avoid detection and blocking by DPI systems. 3. Employ alternative circumvention tools that implement randomized or diverse TLS ClientHello fingerprints to evade DPI detection effectively. 4. Network administrators should implement traffic analysis and anomaly detection to identify and alert on suspicious proxy traffic patterns that may be targeted by DPI. 5. Developers should redesign the TLS handshake implementation in Viber Cloak to incorporate extension diversity and fingerprint randomization, following best practices for cryptographic protocol design. 6. Conduct thorough security audits and penetration testing focusing on cryptographic components to prevent similar vulnerabilities. 7. Educate users in high-risk regions about the risks of using vulnerable versions and recommend safer communication alternatives.
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)