GO-2026-5381 Prometheus vulnerable to stored XSS via crafted histogram bucket label values in the old web UI heatmap display in github.com/prometheus/prometheus

Prometheus vulnerable to stored XSS via crafted histogram bucket label values in the old web UI heatmap display in github.com/prometheus/prometheus...

CVE-2026-44903

CVE-2026-44903 affects Prometheus servers with the legacy web UI enabled. From 2.49.0 up to before 3.5.3 and 3.11.3, histogram heatmap axis tick labels aren’t escaped when inserting metric label values into HTML, allowing an attacker who can inject crafted metrics to run JavaScript in the browser...