VU#212479: Sentry Seer vulnerability allows attacker-controlled input to be executed in a privileged environment

CERT/CC details CVE-2026-90999: attacker-controlled Sentry telemetry can steer the Seer coding agent into executing attacker code with repository access.

CERT/CC published VU#212479 for CVE-2026-90999 in Sentry Seer: attacker-submitted events through public DSN endpoints flow into Seer's root-cause analysis, which is embedded directly into the coding agent's initial prompt. In the documented chain, the privileged coding agent downloads and executes an attacker-controlled package before any human review, yielding arbitrary code execution with access to connected source repositories. No vendor patch is available yet; mitigations include disabling automated remediation, restricting coding-agent package installation, and filtering telemetry before Seer analysis.