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CVE-2025-3857: Critical Denial of Service Vulnerability in Amazon.IonDotnet

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Overview

CVE-2025-3857 is a severe vulnerability in Amazon.IonDotnet’s RawBinaryReader class that could potentially lead to system compromise or data leakage. This vulnerability affects applications using Amazon.IonDotnet for reading binary Ion data, and it poses a significant risk due to its potential to trigger an infinite loop condition, resulting in a denial of service.

Vulnerability Summary

CVE ID: CVE-2025-3857
Severity: High, CVSS 7.5
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise or data leakage

Affected Products

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Product | Affected Versions

Amazon.IonDotnet | All versions prior to 1.3.1

How the Exploit Works

The exploit for this vulnerability involves sending malformed or truncated Ion data to an application using Amazon.IonDotnet. The lack of checks on the number of bytes read from the underlying stream while deserializing the binary format results in an infinite loop condition. This situation can cause system resources to be exhausted, leading to a denial of service. Additionally, in some cases, this vulnerability could be leveraged to compromise the system or leak data.

Conceptual Example Code

Here’s a conceptual example of a malicious payload that could potentially exploit this vulnerability:

POST /api/parse_ion HTTP/1.1
Host: target.example.com
Content-Type: application/ion
{
"malformed_ion_data": "..."
}

In this example, “malformed_ion_data” would contain Ion data that is purposely malformed or truncated to exploit the vulnerability.

Mitigation Guidance

Users are advised to upgrade to Amazon.IonDotnet version 1.3.1 to mitigate this vulnerability. If an immediate upgrade is not possible, the use of a Web Application Firewall (WAF) or Intrusion Detection System (IDS) could serve as a temporary mitigation measure. Ensure any forked or derivative code is patched to incorporate the new fixes.

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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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