Vulnerability · Published Jan 27, 2026 · Assigned by GRAFANA
CVE-2026-21720Unauthenticated DoS: avatar cache leaks goroutines when /avatar/:hash requests time out
High 7.5
In plain English
A high-severity uncontrolled resource consumption in grafana/grafana from Grafana. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Grafana | grafana/grafana-enterprise | 3.0.0 – before 11.6.9 |
| Grafana | grafana/grafana-enterprise | 3.0.0 – before 12.0.8 |
| Grafana | grafana/grafana-enterprise | 3.0.0 – before 12.1.5 |
| Grafana | grafana/grafana | 3.0.0 – before 11.6.9 |
| Grafana | grafana/grafana | 3.0.0 – before 12.0.8 |
| Grafana | grafana/grafana | 3.0.0 – before 12.1.5 |
| Grafana | grafana/grafana-enterprise | 3.0.0 – before 12.2.3 |
| Grafana | grafana/grafana | 3.0.0 – before 12.2.3 |
| Grafana | grafana/grafana-enterprise | 3.0.0 – before 12.3.1 |
| Grafana | grafana/grafana | 3.0.0 – before 12.3.1 |
Weakness: CWE-400, CWE-703, CWE-772 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://grafana.com/security/security-advisories/cve-2026-21720 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-21720 vdb-entry, x_refsource_REDHAT
- RHBZ#2433226 issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21720.json x_sadp-csaf-vex