Bugsink stores an attacker’s JavaScript payload in an event when the event is submitted to a public ingestion endpoint. The payload is delivered unescaped when a stacktrace is rendered because a known Pygments quirk causes raw lines to be returned and then marked safe. An attacker cannot directly exploit the vulnerability, but the stored code runs in the context of an administrator who explicitly views the event in the web UI, granting the attacker the administrator’s privileges within Bugsink.

All Bugsink installations running a version earlier than 2.0.13 are affected. The issue is present in the Bugsink Bugsink product, and no specific operating system or deployment environment is required beyond the ability to host Bugsink and expose the ingest endpoint. Deployments that use the public DSN endpoint for event submission are vulnerable because no authentication is needed to upload events.

The CVSS score of 9.3 indicates a severe vulnerability with full impact on confidentiality, integrity and availability. The EPSS score is less than 1%, so current exploitation likelihood is very low; however, the exploitation path is simple: an attacker must know or obtain the DSN back‑end, submit an event containing malicious code, and wait until an administrator opens the event in the UI. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog, but the high score warrants rapid remediation. The attack vector is remote and requires only public access to the ingestion endpoint, which is normally open for third‑party clients.