CVE-2026-21720

Description

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.

CVSS Metrics

• v3.1•HIGH•Score: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.04%• Percentile: 11%

Techniques & Countermeasures

• CWE-400•Uncontrolled Resource Consumption

  The product does not properly control the allocation and maintenance of a limited resource.

• CWE-703•Improper Check or Handling of Exceptional Conditions

  The product does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the product.

Affected Systems

• grafana•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

• grafana•grafana/grafana

  ≥ 3.0.0, < 11.6.9 | ≥ 3.0.0, < 12.0.8 | ≥ 3.0.0, < 12.1.5 | ≥ 3.0.0, < 12.2.3 | ≥ 3.0.0, < 12.3.1

• grafana•grafana/grafana-enterprise

  ≥ 3.0.0, < 11.6.9 | ≥ 3.0.0, < 12.0.8 | ≥ 3.0.0, < 12.1.5 | ≥ 3.0.0, < 12.2.3 | ≥ 3.0.0, < 12.3.1

References (2)

• https://grafana.com/security/security-advisories/CVE-2026-21720
• https://grafana.com/security/security-advisories/cve-2026-21720