Description

In JetBrains Toolbox App before 3.9 insufficient warning in the login dialog allowed connecting to a malicious server

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "3.1",
  "pubDate": "2026-11-06T11:17:11.593Z",
  "pubdate": "2026-11-06T11:17:11.593Z",
  "executiveSummary": "A vulnerability exists in JetBrains Toolbox App prior to version 3.9, categorized as an insufficient warning/authentication bypass issue. The flaw resides within the application's login dialog mechanism, which fails to adequately alert or prevent users from connecting to untrusted or malicious remote servers. This lack of validation facilitates a scenario where an attacker can orchestrate a man-in-the-middle (MitM) position or lure a user into authenticating against a rogue server. Successful exploitation allows for the interception of sensitive authentication tokens, credentials, or session data transmitted during the login handshake. The vulnerability impacts all users of the affected JetBrains Toolbox App versions and presents a significant risk regarding data exfiltration and credential compromise. Attackers do not require complex administrative privileges but do need to facilitate the redirection of the application to a malicious endpoint, typically through network manipulation or social engineering tactics that entice the user to interact with a deceptive login interface.",
  "technicalDetails": "The vulnerability originates from inadequate validation and warning implementation within the JetBrains Toolbox App's login dialog component. In affected versions (pre-3.9), the application logic responsible for establishing connections during the authentication lifecycle fails to properly verify the authenticity of the target server, nor does it provide sufficient security warnings when a non-standard or untrusted server address is utilized. This failure creates an 'Insecure Connection' state where the client-side software does not mandate secure communication channels or trusted certificate validation before transmitting sensitive authentication payloads.\nThe attack flow commences when an adversary influences the application's connection parameters to point to a malicious server under their control. This can be achieved through various vectors, including but not limited to, manipulating local configuration files, leveraging malicious links, or intercepting DNS queries to redirect traffic. Once the login dialog is triggered against the adversary-controlled server, the application proceeds to initiate an authentication handshake. Because the application lacks the necessary validation logic to inspect server identity or warn the user about the insecure connection, it silently proceeds to exchange sensitive data, including OAuth tokens, API keys, or plaintext credentials.\nThe component responsible for this behavior is the core authentication handler within the Toolbox App, which lacks the granular integrity checking expected in modern client-server interactions. The lack of an explicit, unavoidable warning mechanism means that the application behaves as if it were communicating with an authorized JetBrains infrastructure, regardless of the server's actual cryptographic identity. Consequently, the application becomes susceptible to credential harvesting, as the adversary acts as a transparent proxy. The post-exploitation impact includes the full compromise of the user's JetBrains account, enabling unauthorized access to private repositories, subscription details, and potentially further lateral movement into the user's development environment if associated service integrations are active. The absence of strict mutual TLS (mTLS) or robust server-side certificate pinning in the affected dialog sequence allows this unauthorized communication to persist without triggering security alerts, thereby maintaining the integrity of the attacker's deception until successful data extraction is completed."
}