An unauthenticated attacker who can submit events to a Bugsink project can store arbitrary JavaScript in an event. The payload executes only if a user explicitly views the affected Stacktrace in the web UI.
In affected versions, a specially crafted Brotli-compressed envelope can cause Bugsink to spend excessive CPU time in decompression, leading to denial of service. This can be done if the DSN is known, which it is in many common setups (JavaScript, Mobile Apps).
In affected versions, brotli "bombs" (highly compressed brotli streams, such as many zeros) can be sent to the server. Since the server will attempt to decompress these streams before applying various maximums, this can lead to exhaustion of the available memory and thus a Denial of Service. This can be done if the DSN is known, which it is in many common setups (JavaScript, Mobile Apps).
In affected versions, ingestion paths construct file locations directly from untrusted event_id input without validation. A specially crafted event_id can result in paths outside the intended directory, potentially allowing file overwrite or creation in arbitrary locations. Submitting such input requires access to a valid DSN. While that limits exposure, DSNs are sometimes discoverable—for example, when included in frontend code—and should not be treated as a strong security boundary.