Executive brief
Grafana is a popular platform used for monitoring and visualizing data. A flaw in how it handles user profile pictures (avatars) allows an unauthenticated attacker to crash the server by sending a flood of specific requests. This can lead to a total service outage, preventing teams from monitoring their infrastructure.
Technical details
A denial of service vulnerability exists in Grafana's avatar caching component. Every uncached request to the '/avatar/:hash' endpoint spawns a goroutine to refresh the image from Gravatar. If the refresh task remains in the 10-slot worker queue for more than three seconds, the handler times out and stops listening, causing the goroutine to block indefinitely on an unbuffered channel. An attacker can exploit this by sending sustained traffic with random hashes, leading to linear goroutine growth and eventual memory exhaustion. The issue is fixed in versions 11.6.9, 12.0.8, 12.1.5, 12.2.3, and 12.3.1.
Affected products
- Grafana Labs Grafana >=3.0.0, <11.6.9; >=12.0.0, <12.0.8; >=12.1.0, <12.1.5; >=12.2.0, <12.2.3; >=12.3.0, <12.3.1
- Grafana Labs Grafana Enterprise >=3.0.0, <11.6.9; >=12.0.0, <12.0.8; >=12.1.0, <12.1.5; >=12.2.0, <12.2.3; >=12.3.0, <12.3.1
Timeline
- 2026-01-27: disclosed
- 2026-01-27: advisory