Description

In JetBrains Hub before 2026.2.52556 sMTP command injection via email verification was possible

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.0",
  "pubDate": "2026-11-06T11:17:08.660Z",
  "pubdate": "2026-11-06T11:17:08.660Z",
  "executiveSummary": "JetBrains Hub contains a vulnerability allowing SMTP command injection during the email verification process.\nThis vulnerability is classified as an injection flaw, specifically affecting the interaction between the application and the configured SMTP server.\nBy manipulating input fields processed by the email verification component, an attacker can inject arbitrary SMTP commands.\nSuccessful exploitation may allow attackers to bypass security controls, potentially leading to unauthorized email relaying or communication interception.\nThe vulnerability affects all versions of JetBrains Hub prior to 2026.2.52556.\nExploitation generally requires access to the application's email configuration settings or the ability to influence input handled by the email verification workflow.\nThe risk implication is significant as it undermines the integrity of the application's outbound mail communication and could facilitate phishing or data exfiltration campaigns.",
  "technicalDetails": "The vulnerability originates from improper neutralization of special characters and control sequences within the user-supplied data handled by the email verification subsystem in JetBrains Hub.\nWhen JetBrains Hub initiates an email verification process, it constructs an SMTP transaction. If the application fails to properly sanitize inputs before passing them to the underlying SMTP client library or directly to the mail server, an attacker can inject malicious SMTP commands.\nThe attack flow typically involves a user providing crafted input into fields that are subsequently used in the SMTP 'MAIL FROM', 'RCPT TO', or 'DATA' commands. By inserting CRLF (Carriage Return/Line Feed) sequences, an attacker can terminate the intended command and inject new, unauthorized SMTP commands.\nFor example, by injecting 'rn' followed by 'RCPT TO: attacker@example.com', the attacker can force the mail server to send copies of system-generated emails to an arbitrary recipient, potentially leading to the disclosure of sensitive information contained within verification emails, such as password reset tokens or validation codes.\nThis injection flaw essentially allows for the manipulation of the SMTP session state. Because the application interacts directly with the SMTP transport layer, the lack of robust input validation means that the application acts as a proxy for the attacker's malicious commands.\nThe vulnerable component resides within the core email notification service responsible for generating and dispatching outgoing communications. The issue affects all versions prior to 2026.2.52556, indicating a lack of secure SMTP handling practices in earlier release cycles.\nSuccessful exploitation may not require high-level administrative privileges if the input field is publicly accessible during the verification request; however, the attacker must be able to interact with the SMTP-sending functionality of the Hub instance.\nPost-exploitation, the impact ranges from unauthorized mail relaying to social engineering via forged email origins. If the SMTP server lacks strict authentication or relay restrictions, the impact is magnified, as the attacker can leverage the trusted status of the application server to bypass anti-spam filters."
}