JetBrains YouTrack EUVD-2026-33416

Exploitation requires an authenticated YouTrack account (PR:L) with sufficient project-level permission to create or modify notification templates within at least one project, plus a victim user (UI:R) who subsequently triggers rendering of the poisoned template by receiving or viewing the resulting notification. Limiting factors: the attacker must have write access to the notification-template surface (typically project admin or a delegated role rather than a basic reporter), the victim must actually open the notification in an authenticated context, and instances on the fixed 2026.1.13162 build or later are not exploitable; the attack does not require any non-default configuration of YouTrack itself.

The CVSS 8.7 vector AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N tells a coherent story: network-reachable, low complexity, requires a low-privileged authenticated account, requires victim interaction (viewing the notification), and crucially has a changed scope with high confidentiality and integrity impact - consistent with stored XSS hijacking a more privileged user's session. EPSS data was not provided, the CVE is not listed in CISA KEV, and there is no public POC evidence in the supplied intelligence, so real-world exploitation pressure is currently low-to-moderate. The practical priority is elevated for organizations whose YouTrack instances are internet-exposed or have many low-trust project members who can author templates, because a single malicious template can compromise administrators; conversely, instances where template-editing rights are tightly restricted face significantly lower realistic risk than the headline score suggests.

An attacker with a low-privileged YouTrack account that has rights to edit a project's notification templates inserts a malicious script payload into a template field. When a project administrator or other higher-privileged user later receives or views a notification rendered from that template, the script executes in their authenticated browser session, allowing the attacker to exfiltrate the session token, read sensitive issue data, or perform actions on behalf of the victim - including, given the scope change, actions outside the original project context.