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CVE-2025-30403: Heap-buffer-overflow Vulnerability in mvfst Impacts QUIC Sessions

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Overview

Recently, a security vulnerability identified as CVE-2025-30403 has been discovered in the mvfst library, an open source QUIC protocol implementation by Facebook. This vulnerability can potentially lead to system compromise or data leakage, making it a critical concern for any organizations or individuals using affected versions of mvfst. The mvfst library is widely adopted in various applications that require reliable transport of data over the internet, making the impact of this vulnerability potentially far-reaching.

Vulnerability Summary

CVE ID: CVE-2025-30403
Severity: High (8.1 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: Required
Impact: Potential system compromise or data leakage

Affected Products

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Product | Affected Versions

mvfst | Versions prior to v2025.07.07.00

How the Exploit Works

The vulnerability lies in the mvfst’s handling of incoming messages during a QUIC session. A specially crafted message can trigger a heap-buffer-overflow in mvfst, causing the system to behave unexpectedly or even crash. This could potentially allow an attacker to execute arbitrary code or leak sensitive information from the system memory.

Conceptual Example Code

A potential exploit could involve sending a maliciously crafted QUIC message that would trigger the heap-buffer-overflow. The example below illustrates a conceptual malicious payload:

# Conceptual example of a malicious QUIC message
quic_send --target=target.example.com --port=4433 --payload='{"malicious_payload": "..." }'

Please note that this is a conceptual example and the `quic_send` command does not actually exist. It is used here for illustrative purposes only to show how a malicious payload could be sent to a target via a QUIC message.

Mitigation and Remediation

The best way to mitigate this vulnerability is to apply the patch provided by the vendor. Users of mvfst should upgrade to version v2025.07.07.00 or later which contains a fix for this vulnerability.
In the meantime, as a temporary mitigation, users can use a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to detect and block any suspicious QUIC messages that might attempt to exploit this vulnerability. However, this should not be considered a long-term solution as it may not be 100% effective and can potentially introduce performance overhead.

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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.

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