CVE-2025-57733 in TeamCity
Summary
by MITRE • 08/20/2025
In JetBrains TeamCity before 2025.07.1 sMTP injection was possible allowing modification of email content
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Analysis
by VulDB Data Team • 08/23/2025
The vulnerability identified as CVE-2025-57733 represents a critical security flaw in JetBrains TeamCity versions prior to 2025.07.1 that enables smtp injection attacks. This vulnerability allows authenticated attackers to manipulate email content through carefully crafted input that bypasses normal sanitization mechanisms. The flaw specifically affects the email handling functionality within the TeamCity platform, which is widely used for continuous integration and delivery processes across enterprise environments. The security implications are particularly severe given that TeamCity serves as a central hub for software development workflows where email notifications are frequently used for build status alerts, deployment notifications, and system communications.
The technical root cause of this vulnerability stems from insufficient input validation and sanitization within the email processing pipeline. When TeamCity generates and sends emails, it processes user-provided data that may contain malicious payloads designed to exploit the smtp injection mechanism. This allows attackers to inject additional headers, modify existing email content, or even redirect email recipients through carefully constructed input fields. The vulnerability operates at the application layer and specifically targets the email generation and transmission components that handle user-defined parameters in build configurations, notification settings, and project descriptions. This type of injection vulnerability is categorized under CWE-94, which describes improper control of generation of code, and more specifically aligns with CWE-74, representing improper neutralization of special elements used in data queries.
The operational impact of CVE-2025-57733 extends beyond simple email manipulation to potentially compromise the integrity of entire development workflows. Attackers could exploit this vulnerability to send phishing emails that appear to originate from legitimate TeamCity sources, manipulate build status notifications to hide failures, or redirect critical alerts to unauthorized recipients. This could lead to security incidents where developers are misled about the true state of their applications or where sensitive information is disclosed through manipulated email communications. The vulnerability is particularly dangerous in environments where TeamCity is configured to send emails to external stakeholders or where automated email notifications are integrated with other security systems. According to ATT&CK framework, this vulnerability maps to technique T1190 - Exploit Public-Facing Application, and could enable additional techniques such as T1566 - Phishing and T1078 - Valid Accounts through the manipulation of email communications.
Organizations using affected TeamCity versions should immediately implement mitigations including upgrading to the patched 2025.07.1 release or later, which includes enhanced input validation and sanitization measures. Additionally, administrators should review email configuration settings to limit the scope of user-controlled input that can influence email content generation. Network segmentation and monitoring of email traffic can help detect potential exploitation attempts, while regular security audits of TeamCity configurations should be conducted to ensure proper email handling procedures are in place. The vulnerability demonstrates the critical importance of input validation in security-critical applications and highlights the need for comprehensive security testing of email processing components in enterprise software platforms. Organizations should also consider implementing email authentication mechanisms such as DKIM and DMARC to provide additional protection against email spoofing and manipulation attacks that could exploit this vulnerability.