CVE-2026-21720
Unauthenticated DoS: avatar cache leaks goroutines when /avatar/:hash requests time out
Severity Score
7.5
*CVSS v3.1
Exploit Likelihood
*EPSS
Affected Versions
*CPE
Public Exploits
0
*Multiple Sources
Exploited in Wild
-
*KEV
Decision
Attend
*SSVC
Descriptions
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.
*Credits:
N/A
CVSS Scores
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
Attack Vector
Attack Complexity
Authentication
Confidentiality
Integrity
Availability
* Common Vulnerability Scoring System
SSVC
- Decision:Attend
Exploitation
Automatable
Tech. Impact
* Organization's Worst-case Scenario
Timeline
- 2026-01-05 CVE Reserved
- 2026-01-27 CVE Published
- 2026-05-13 CVE Updated
- 2026-05-13 EPSS Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
- CWE-400: Uncontrolled Resource Consumption
- CWE-703: Improper Check or Handling of Exceptional Conditions
CAPEC
References (2)
| URL | Date | SRC |
|---|
| URL | Date | SRC |
|---|
| URL | Date | SRC |
|---|---|---|
| https://grafana.com/security/security-advisories/cve-2026-21720 | 2026-05-13 |
Affected Vendors, Products, and Versions
| Vendor | Product | Version | Other | Status | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
| Grafana Search vendor "Grafana" | Grafana/grafana-enterprise Search vendor "Grafana" for product "Grafana/grafana-enterprise" | >= 3.0.0 < 11.6.9 Search vendor "Grafana" for product "Grafana/grafana-enterprise" and version " >= 3.0.0 < 11.6.9" | en |
Affected
| ||||||
| Grafana Search vendor "Grafana" | Grafana/grafana-enterprise Search vendor "Grafana" for product "Grafana/grafana-enterprise" | >= 3.0.0 < 12.0.8 Search vendor "Grafana" for product "Grafana/grafana-enterprise" and version " >= 3.0.0 < 12.0.8" | en |
Affected
| ||||||
| Grafana Search vendor "Grafana" | Grafana/grafana-enterprise Search vendor "Grafana" for product "Grafana/grafana-enterprise" | >= 3.0.0 < 12.1.5 Search vendor "Grafana" for product "Grafana/grafana-enterprise" and version " >= 3.0.0 < 12.1.5" | en |
Affected
| ||||||
| Grafana Search vendor "Grafana" | Grafana/grafana Search vendor "Grafana" for product "Grafana/grafana" | >= 3.0.0 < 11.6.9 Search vendor "Grafana" for product "Grafana/grafana" and version " >= 3.0.0 < 11.6.9" | en |
Affected
| ||||||
| Grafana Search vendor "Grafana" | Grafana/grafana Search vendor "Grafana" for product "Grafana/grafana" | >= 3.0.0 < 12.0.8 Search vendor "Grafana" for product "Grafana/grafana" and version " >= 3.0.0 < 12.0.8" | en |
Affected
| ||||||
| Grafana Search vendor "Grafana" | Grafana/grafana Search vendor "Grafana" for product "Grafana/grafana" | >= 3.0.0 < 12.1.5 Search vendor "Grafana" for product "Grafana/grafana" and version " >= 3.0.0 < 12.1.5" | en |
Affected
| ||||||
| Grafana Search vendor "Grafana" | Grafana/grafana-enterprise Search vendor "Grafana" for product "Grafana/grafana-enterprise" | >= 3.0.0 < 12.2.3 Search vendor "Grafana" for product "Grafana/grafana-enterprise" and version " >= 3.0.0 < 12.2.3" | en |
Affected
| ||||||
| Grafana Search vendor "Grafana" | Grafana/grafana Search vendor "Grafana" for product "Grafana/grafana" | >= 3.0.0 < 12.2.3 Search vendor "Grafana" for product "Grafana/grafana" and version " >= 3.0.0 < 12.2.3" | en |
Affected
| ||||||
| Grafana Search vendor "Grafana" | Grafana/grafana-enterprise Search vendor "Grafana" for product "Grafana/grafana-enterprise" | >= 3.0.0 < 12.3.1 Search vendor "Grafana" for product "Grafana/grafana-enterprise" and version " >= 3.0.0 < 12.3.1" | en |
Affected
| ||||||
| Grafana Search vendor "Grafana" | Grafana/grafana Search vendor "Grafana" for product "Grafana/grafana" | >= 3.0.0 < 12.3.1 Search vendor "Grafana" for product "Grafana/grafana" and version " >= 3.0.0 < 12.3.1" | en |
Affected
| ||||||