CVE-2025-57733 is a medium-severity vulnerability identified in JetBrains TeamCity versions prior to 2025.07.1. The vulnerability is classified under CWE-77, which corresponds to Improper Neutralization of Special Elements used in a Command ('Command Injection'). Specifically, this flaw allows for SMTP injection, enabling an attacker with certain privileges to manipulate the content of emails sent by the TeamCity server. TeamCity is a widely used continuous integration and continuous delivery (CI/CD) server that automates build and deployment processes. The vulnerability arises because the SMTP email functionality does not properly sanitize or validate input parameters, allowing an attacker with high privileges (PR:H) to inject arbitrary SMTP commands or modify email content. The CVSS v3.1 score of 5.5 reflects a medium severity, with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), requiring privileges (PR:H), no user interaction (UI:N), and a scope change (S:C). The impact affects confidentiality and integrity (C:L/I:L) but not availability (A:N). No known exploits are reported in the wild yet, and no official patches or mitigation links were provided at the time of publication. The vulnerability could be exploited by authenticated users with elevated privileges to alter email notifications, potentially leading to phishing, misinformation, or social engineering attacks within an organization’s CI/CD pipeline communications.

For European organizations, the impact of CVE-2025-57733 can be significant, especially for those relying heavily on JetBrains TeamCity for their software development lifecycle. The ability to modify email content can undermine trust in automated notifications, which are often used for build statuses, deployment alerts, and security warnings. Attackers could leverage this to send misleading or malicious emails that appear legitimate, facilitating phishing campaigns or spreading false information internally. This could lead to compromised credentials, unauthorized access, or disruption of development workflows. Furthermore, the scope change in the vulnerability means that the attacker could potentially affect components beyond their initial privileges, increasing the risk of lateral movement or privilege escalation within the network. Given the critical role of CI/CD pipelines in modern software development, any compromise can delay releases, introduce vulnerabilities into production, or cause compliance issues with European data protection regulations such as GDPR if sensitive information is leaked or manipulated.

To mitigate this vulnerability, European organizations should: 1) Immediately upgrade JetBrains TeamCity to version 2025.07.1 or later once available, as this version addresses the SMTP injection flaw. 2) Restrict high-privilege access to TeamCity to only trusted administrators and enforce strong authentication mechanisms such as multi-factor authentication (MFA). 3) Audit and monitor email notification configurations and logs for unusual or unauthorized changes in email content or recipients. 4) Implement network segmentation to limit access to the TeamCity server and its SMTP services, reducing exposure to potential attackers. 5) Educate development and operations teams about the risks of phishing and social engineering attacks that could arise from manipulated CI/CD notifications. 6) Consider deploying email security solutions that can detect and block suspicious or malformed emails originating from internal systems. 7) Regularly review and update security policies related to CI/CD tools and their integrations to ensure timely patching and vulnerability management.