GitHub Security Advisories (GHSA) have become a central component of open-source vulnerability disclosure, influencing the security posture of millions of users. A distinctive feature of GHSA is that only a fraction of advisories are reviewed by GitHub, and the prioritization mechanisms behind this process remain poorly understood. In this paper, we conduct a large-scale empirical study of GHSA review processes, analyzing over 288,000 advisories spanning 2019-2025. We characterize which advisories are more likely to be reviewed, quantify review delays, and reveal the existence of two distinct latency regimes: a fast path dominated by GitHub Repository Advisories (GRAs) and a slow path dominated by NVD-first advisories. We then develop a queueing model that explains this dichotomy as an emergent property of the pipeline’s structure. Our findings highlight how disclosure strategies affect review speed and offer actionable insights for improving vulnerability triage and response in open-source ecosystems.