Label Studio 1.22.0 and earlier contains a persistent stored cross‑site scripting flaw in the custom_hotkeys configuration field. When an attacker can inject malicious JavaScript through this field—either by authenticating to the system or by persuading a user to modify their hotkeys—the code executes in the browsers of every user who visits any page that renders the templates/base.html template. Because the application exposes an API token endpoint (/api/current-user/token) and does not provide robust CSRF protection on several token‑related routes, the injected script can fetch or reset the victim’s API token, granting the attacker full control over the compromised account and unrestricted programmatic access.

The affected product is HumanSignal Label Studio version 1.22.0 and all earlier releases. The description does not specify a patch version, but the vulnerability is limited to these pre‑1.22.0 releases.

The CVSS score of 8.6 indicates a high severity potential. The EPSS score of less than 1% suggests that exploitation in the wild is expected to be rare, and the vulnerability is not listed in CISA’s KEV catalog. The attack vector is browser‑based; an attacker only needs to inject the malicious custom_hotkeys payload from an authenticated session or convince a user to do so. Once the payload is present, other users who load pages using the base template are impacted, and the script can exfiltrate API tokens or trigger a reset, enabling full account takeover.