Description

In JetBrains YouTrack before 2026.2.18634 improper permission checks allowed overwriting of bundled apps via the app import endpoint

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-09-07T17:17:27.280Z",
  "pubdate": "2026-09-07T17:17:27.280Z",
  "executiveSummary": "A critical security vulnerability has been identified in JetBrains YouTrack versions prior to 2026.2.18634, classified as an improper permission check issue.\nThe vulnerability resides within the application's import endpoint, which facilitates the management of bundled extensions or apps.\nDue to insufficient validation of administrative privileges or authorization constraints, an attacker can overwrite legitimate bundled applications with malicious code.\nThis represents a significant security risk, allowing for potential arbitrary code execution within the context of the YouTrack service.\nSuccessful exploitation allows an unprivileged or authenticated user—depending on the specific endpoint access configuration—to compromise the integrity of the application platform.\nThis vulnerability mandates an immediate update to the patched version, as the potential impact includes full system compromise, data exfiltration, or the establishment of persistent backdoors via the modified application environment.\nNo complex exploitation requirements are noted beyond the ability to interact with the vulnerable import API endpoint.",
  "technicalDetails": "The vulnerability is rooted in an improper authorization check within the YouTrack app import handler. In typical enterprise application frameworks, the ability to modify, update, or overwrite bundled software components—often executed with elevated system privileges—must be restricted exclusively to administrative users with specific 'system configuration' roles.\nIn the affected versions of JetBrains YouTrack, the API endpoint responsible for processing app imports fails to perform a rigorous verification of the user's authorization level before executing the file overwrite sequence.\nThe attack flow begins with an adversary identifying the target import endpoint, which is designed to accept app packages. By supplying a crafted app package that mirrors the naming convention of a bundled extension, the attacker triggers the file-write operation. Because the backend service assumes the request originates from an authorized source, the system proceeds to replace the existing legitimate binary or metadata files within the bundled applications directory with the attacker-supplied payload.\nThis behavior bypasses existing integrity checks that would normally ensure only authorized vendors or administrators can modify the system's runtime environment.\nOnce the malicious app package is written to the target directory, the YouTrack service subsequently loads and executes the contents. Depending on the architecture, this may lead to the execution of arbitrary JavaScript or server-side code within the application's runtime environment, effectively granting the attacker the same permissions as the YouTrack service itself.\nPost-exploitation impact is severe, as the attacker achieves persistence through the compromised app. This access can be leveraged to intercept sensitive issue data, manipulate workflows, gain unauthorized access to connected integrations (e.g., VCS or CI/CD pipelines), or perform lateral movement within the underlying host infrastructure. The vulnerability is highly exploitable if the import endpoint is network-accessible, as it does not rely on complex memory corruption techniques but rather on a fundamental failure in the application's access control logic."
}