CVE-2026-21720 HIGH

CVE-2026-21720: Unauthenticated DoS: avatar cache leaks goroutines when /avatar/:hash requests time out

Vendor Grafana
Product grafana/grafana-enterprise
Published January 27, 2026
Last update June 30, 2026

CVSS base score

7.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

January 27, 2026 CVE published
June 30, 2026 Record updated