CVE-2026-21720
High
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.
SeverityHigh
CVSS7.5
Exploit probability—
Product
Grafana
PublishedJan 27, 2026
First seenJan 27, 2026
How to fix
Update
- grafana grafana11.6.9, 12.0.8, 12.1.5, 12.2.3 or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| grafana grafana | 3.0.0 ≤ v < 11.6.9, 12.0.0 ≤ v < 12.0.8, 12.1.0 ≤ v < 12.1.5, 12.2.0 ≤ v < 12.2.3, 12.3.0 | 11.6.9, 12.0.8, 12.1.5, 12.2.3 |
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