CVE-2026-21720
Unauthenticated DoS: avatar cache leaks goroutines when /avatar/:hash requests time out
7.5
HIGH
CVSS 3.1
EPSS 0.04%
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.
How to fix CVE-2026-21720
To remediate CVE-2026-21720, upgrade the affected package to a fixed version below.
- —upgrade to 11.6.9 or later
Is CVE-2026-21720 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 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
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |