Ameeba Exploit Tracker

Tracking CVEs, exploits, and zero-days for defensive cybersecurity research.

Ameeba Blog Search
TRENDING · 1 WEEK
Attack Vector
Vendor
Severity

CVE-2025-21605: Unauthenticated Client Buffer Overflow Vulnerability in Redis

Views: 35
Ameeba Chat Store screens
Download Ameeba Chat

Overview

This report examines the critical vulnerability, CVE-2025-21605, which affects Redis, an open-source in-memory database. By exploiting this vulnerability, an unauthenticated client can trigger unlimited growth of output buffers, causing the server to exhaust memory or be killed. This vulnerability presents a significant risk to any organization using affected Redis versions, as it could potentially lead to system compromise or data leakage.

Vulnerability Summary

CVE ID: CVE-2025-21605
Severity: High, CVSS score 7.5
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

Ameeba Chat Icon Escape the Surveillance Era

Most apps won’t tell you the truth.
They’re part of the problem.

Phone numbers. Emails. Profiles. Logs.
It’s all fuel for surveillance.

Ameeba Chat gives you a way out.

  • • No phone number
  • • No email
  • • No personal info
  • • Anonymous aliases
  • • End-to-end encrypted

Chat without a trace.

Product | Affected Versions

Redis | 2.6 to 7.4.2

How the Exploit Works

The exploit takes advantage of the default Redis configuration that does not limit the output buffer of normal clients. An unauthenticated client can connect to the Redis server and cause unlimited growth of output buffers, even without providing a password. The output buffer grows from “NOAUTH” responses until the system runs out of memory. This eventually leads to service exhaustion and unavailability of memory.

Conceptual Example Code

The following pseudo command represents how the vulnerability might be exploited:

redis-cli -h target.example.com append NOAUTH "[large string of characters]"

In this example, an attacker continually appends a large string of characters to the ‘NOAUTH’ command, causing the output buffer to grow indefinitely.

Mitigation

The issue has been patched in Redis version 7.4.3. Users are urged to update to the patched version as soon as possible. If immediate patching is not feasible, users are advised to implement network access control tools such as firewalls, iptables, or security groups to block unauthenticated users from connecting to Redis. Alternatively, enabling TLS and requiring users to authenticate using client-side certificates can also help mitigate this vulnerability. As a temporary measure, a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can be used to detect and prevent potential exploitation attempts.

Want to discuss this further? Join the Ameeba Cybersecurity Group Chat.

Disclaimer:

The information and code presented in this article are provided for educational and defensive cybersecurity purposes only. Any conceptual or pseudocode examples are simplified representations intended to raise awareness and promote secure development and system configuration practices.

Do not use this information to attempt unauthorized access or exploit vulnerabilities on systems that you do not own or have explicit permission to test.

Ameeba and its authors do not endorse or condone malicious behavior and are not responsible for misuse of the content. Always follow ethical hacking guidelines, responsible disclosure practices, and local laws.

More posts

Ameeba Chat