Overview
This report discusses the cybersecurity vulnerability CVE-2025-6203, a critical issue affecting Vault servers. This vulnerability allows a malicious user to send a specially-crafted complex payload that meets the default request size limit but leads to excessive memory and CPU consumption. This can cause Vault servers to become unresponsive, potentially leading to system compromise or data leakage.
Vulnerability Summary
CVE ID: CVE-2025-6203
Severity: High (CVSS: 7.5)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Excessive memory and CPU consumption causing server unresponsiveness, potential system compromise or data leakage.
Affected Products
A new way to communicate
Ameeba Chat is built on encrypted identity, not personal profiles.
Message, call, share files, and coordinate with identities kept separate.
- • Encrypted identity
- • Ameeba Chat authenticates access
- • Aliases and categories
- • End-to-end encrypted chat, calls, and files
- • Secure notes for sensitive information
Private communication, rethought.
Product | Affected Versions
Vault Community Edition | Prior to 1.20.3
Vault Enterprise | Prior to 1.20.3, 1.19.9, 1.18.14, and 1.16.25
How the Exploit Works
The exploit takes advantage of the request processing mechanism of Vault servers. By crafting a complex payload that still meets the default request size limit, a malicious actor can cause the server to consume excessive memory and CPU resources. This leads to a timeout in Vault’s auditing subroutine, causing the server to become unresponsive and potentially leading to a system compromise or data leakage.
Conceptual Example Code
The vulnerability might be exploited using a HTTP POST request with a complex payload, as shown below:
POST /vault/processing HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "complex_payload": "..." }In this example, the “complex_payload” parameter contains the specially crafted payload designed to exploit the vulnerability.
Mitigation Guidance
The best mitigation strategy is to apply the patch provided by the vendor. Affected versions should be updated to Vault Community Edition 1.20.3 or Vault Enterprise 1.20.3, 1.19.9, 1.18.14, and 1.16.25. As a temporary mitigation measure, a Web Application Firewall (WAF) or Intrusion Detection System (IDS) could be used to help filter out malicious payloads.