Grafana Goroutine Leak on /avatar/:hash Gravatar Refresh
CVE-2026-21720 Published on January 27, 2026
Unauthenticated DoS: avatar cache leaks goroutines when /avatar/:hash requests time out
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.
Weakness Types
What is a Resource Exhaustion Vulnerability?
The software does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.
CVE-2026-21720 has been classified to as a Resource Exhaustion vulnerability or weakness.
Improper Check or Handling of Exceptional Conditions
The software does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the software.
Products Associated with CVE-2026-21720
Want to know whenever a new CVE is published for Grafana Labs Grafana? stack.watch will email you.
Affected Versions
grafana/grafana-enterprise:- Version 3.0.0 and below 11.6.9 is affected.
- Version 3.0.0 and below 12.0.8 is affected.
- Version 3.0.0 and below 12.1.5 is affected.
- Version 3.0.0 and below 11.6.9 is affected.
- Version 3.0.0 and below 12.0.8 is affected.
- Version 3.0.0 and below 12.1.5 is affected.
- Version 3.0.0 and below 12.2.3 is affected.
- Version 3.0.0 and below 12.2.3 is affected.
- Version 3.0.0 and below 12.3.1 is affected.
- Version 3.0.0 and below 12.3.1 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.