CVE-2026-21720: Grafana

High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days.

Every uncached /avatar/:hash request spawns a goroutine that refreshes the Gravatar image. If the refresh sits in the 10-slot worker queue longer than three seconds, the handler times out and stops listening for the result, so that goroutine blocks forever trying to send on an unbuffered channel. Sustained traffic with random hashes keeps tripping this timeout, so goroutine count grows linearly, eventually exhausting memory and causing Grafana to crash on some systems.

Affected products

• Grafana Grafana: from 3.0.0, before 11.6.9 (fixed in 11.6.9); from 12.0.0, before 12.0.8 (fixed in 12.0.8); from 12.1.0, before 12.1.5 (fixed in 12.1.5); from 12.2.0, before 12.2.3 (fixed in 12.2.3); version 12.3.0 only

Published 2026-01-27. Last modified 2026-07-15.