CVE-2026-100280 in YouTrack
Summary
by MITRE • 09/30/2026
In JetBrains YouTrack before 2026.2.19197 creating a project from an unreadable custom template was possible
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Analysis
by VulDB Data Team • 09/30/2026
The vulnerability identified in JetBrains YouTrack prior to version 2026.2.19197 represents a significant flaw in the application's input validation and error handling mechanisms regarding project initialization processes. Specifically, the system allowed users to create new projects based on custom templates that contained unreadable or malformed data structures. This behavior indicates a failure to properly sanitize or validate template inputs before they were processed by the core engine responsible for instantiating project configurations. In secure software design, any external input, particularly one as critical as a project template which dictates workflow rules, field definitions, and permission schemes, must undergo rigorous validation against expected schemas and data integrity checks. The absence of these safeguards permitted the ingestion of corrupted or non-compliant template files, leading to undefined behavior within the application state management layer.
From a technical perspective, this flaw aligns with CWE-20 Improper Input Validation, as the system failed to reject invalid inputs that did not conform to the expected format for custom templates. Furthermore, it relates closely to CWE-755: Improper Handling of Exceptional Conditions, where the application attempted to proceed with project creation despite encountering data anomalies that should have triggered a rollback or an explicit error message rather than allowing partial or corrupted state persistence. The operational impact of this vulnerability extends beyond simple user experience degradation; it poses risks to system stability and potential security implications if the malformed template triggers unexpected code paths, memory corruption issues, or logic errors in downstream services such as notification engines, workflow automations, or permission evaluators. Attackers with access to upload custom templates could potentially exploit this inconsistency to cause denial of service conditions by exhausting server resources during the parsing phase or to introduce subtle bugs that compromise data integrity within newly created projects.
The exploitation scenario typically involves an authenticated user who possesses permissions to create projects and manage custom templates. By uploading a template file containing invalid XML, JSON, or proprietary binary structures depending on the internal format used by YouTrack for project definitions, the attacker can trigger this vulnerability. While immediate remote code execution is not implied by this specific description, the resulting instability can disrupt team workflows and require administrative intervention to resolve corrupted project states. This type of issue highlights the importance of robust schema validation at every layer of data ingestion within enterprise collaboration tools where configuration drift or corruption can have cascading effects across multiple user accounts and projects.
To mitigate this vulnerability, organizations running versions of YouTrack prior to 2026.2.19197 should prioritize upgrading to the latest patched release immediately upon availability. JetBrains has addressed the underlying logic errors in input validation routines to ensure that only well-formed templates are accepted during project creation processes. In addition to patching, administrators should enforce strict access controls on who can create projects and manage custom templates within their instances. Implementing automated testing for template files before upload, if possible through external CI/CD pipelines or pre-commit hooks in development workflows, adds an additional layer of defense against malformed data entry. Regular audits of project configurations and monitoring system logs for unusual error patterns related to template processing can also help detect any residual issues or attempted exploitation activities. Maintaining up-to-date software is the most effective strategy to prevent such vulnerabilities from impacting operational continuity and security posture.