Unauthenticated DoS: avatar cache leaks goroutines when /avatar/:hash requests time out
Priority MEDIUM 40CWE-400Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-400.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00691 53rd percentileScored 2026-11-07
Fix Fixed grafana/grafana-enterprise (Grafana): 11.6.9, 12.0.8, 12.1.5 +2grafana/grafana (Grafana): 11.6.9, 12.0.8, 12.1.5 +2
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Grafana | grafana/grafana-enterprise | 3.0.0 to before 11.6.9 | 11.6.9 | Patch available | CNA |
| Grafana | grafana/grafana-enterprise | 3.0.0 to before 12.0.8 | 12.0.8 | Patch available | CNA |
| Grafana | grafana/grafana-enterprise | 3.0.0 to before 12.1.5 | 12.1.5 | Patch available | CNA |
| Grafana | grafana/grafana | 3.0.0 to before 11.6.9 | 11.6.9 | Patch available | CNA |
| Grafana | grafana/grafana | 3.0.0 to before 12.0.8 | 12.0.8 | Patch available | CNA |
| Grafana | grafana/grafana | 3.0.0 to before 12.1.5 | 12.1.5 | Patch available | CNA |
| Grafana | grafana/grafana-enterprise | 3.0.0 to before 12.2.3 | 12.2.3 | Patch available | CNA |
| Grafana | grafana/grafana | 3.0.0 to before 12.2.3 | 12.2.3 | Patch available | CNA |
| Grafana | grafana/grafana-enterprise | 3.0.0 to before 12.3.1 | 12.3.1 | Patch available | CNA |
| Grafana | grafana/grafana | 3.0.0 to before 12.3.1 | 12.3.1 | Patch available | CNA |
- grafana/grafana-enterprise VendorGrafana Affected 3.0.0 to before 11.6.9 Fixed in 11.6.9 Patch available CNA
- grafana/grafana-enterprise VendorGrafana Affected 3.0.0 to before 12.0.8 Fixed in 12.0.8 Patch available CNA
- grafana/grafana-enterprise VendorGrafana Affected 3.0.0 to before 12.1.5 Fixed in 12.1.5 Patch available CNA
- grafana/grafana VendorGrafana Affected 3.0.0 to before 11.6.9 Fixed in 11.6.9 Patch available CNA
- grafana/grafana VendorGrafana Affected 3.0.0 to before 12.0.8 Fixed in 12.0.8 Patch available CNA
- grafana/grafana VendorGrafana Affected 3.0.0 to before 12.1.5 Fixed in 12.1.5 Patch available CNA
- grafana/grafana-enterprise VendorGrafana Affected 3.0.0 to before 12.2.3 Fixed in 12.2.3 Patch available CNA
- grafana/grafana VendorGrafana Affected 3.0.0 to before 12.2.3 Fixed in 12.2.3 Patch available CNA
- grafana/grafana-enterprise VendorGrafana Affected 3.0.0 to before 12.3.1 Fixed in 12.3.1 Patch available CNA
- grafana/grafana VendorGrafana Affected 3.0.0 to before 12.3.1 Fixed in 12.3.1 Patch available CNA
CPE configurations NVD · 10
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:* | 3.0.0 to before 11.6.9 | Vulnerable | Grafana |
| cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:* | 3.0.0 to before 11.6.9 | Vulnerable | Grafana |
| cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:* | 12.0.0 to before 12.0.8 | Vulnerable | Grafana |
| cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:* | 12.0.0 to before 12.0.8 | Vulnerable | Grafana |
| cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:* | 12.1.0 to before 12.1.5 | Vulnerable | Grafana |
| cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:* | 12.1.0 to before 12.1.5 | Vulnerable | Grafana |
| cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:* | 12.2.0 to before 12.2.3 | Vulnerable | Grafana |
| cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:* | 12.2.0 to before 12.2.3 | Vulnerable | Grafana |
| cpe:2.3:a:grafana:grafana:12.3.0:*:*:*:-:*:*:* | 12.3.0 | Vulnerable | Grafana |
| cpe:2.3:a:grafana:grafana:12.3.0:*:*:*:enterprise:*:*:* | 12.3.0 | Vulnerable | Grafana |
- cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:* Versions 3.0.0 to before 11.6.9 Vulnerable ·Grafana
- cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:* Versions 3.0.0 to before 11.6.9 Vulnerable ·Grafana
- cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:* Versions 12.0.0 to before 12.0.8 Vulnerable ·Grafana
- cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:* Versions 12.0.0 to before 12.0.8 Vulnerable ·Grafana
- cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:* Versions 12.1.0 to before 12.1.5 Vulnerable ·Grafana
- cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:* Versions 12.1.0 to before 12.1.5 Vulnerable ·Grafana
- cpe:2.3:a:grafana:grafana:*:*:*:*:-:*:*:* Versions 12.2.0 to before 12.2.3 Vulnerable ·Grafana
- cpe:2.3:a:grafana:grafana:*:*:*:*:enterprise:*:*:* Versions 12.2.0 to before 12.2.3 Vulnerable ·Grafana
- cpe:2.3:a:grafana:grafana:12.3.0:*:*:*:-:*:*:* Versions 12.3.0 Vulnerable ·Grafana
- cpe:2.3:a:grafana:grafana:12.3.0:*:*:*:enterprise:*:*:* Versions 12.3.0 Vulnerable ·Grafana
Remediation
- Fix · CNA grafana/grafana-enterprise (Grafana) Fixed in 11.6.9
- Fix · CNA grafana/grafana-enterprise (Grafana) Fixed in 12.0.8
- Fix · CNA grafana/grafana-enterprise (Grafana) Fixed in 12.1.5
- Fix · CNA grafana/grafana (Grafana) Fixed in 11.6.9
- Fix · CNA grafana/grafana (Grafana) Fixed in 12.0.8
- Fix · CNA grafana/grafana (Grafana) Fixed in 12.1.5
- Fix · CNA grafana/grafana-enterprise (Grafana) Fixed in 12.2.3
- Fix · CNA grafana/grafana (Grafana) Fixed in 12.2.3
- Fix · CNA grafana/grafana-enterprise (Grafana) Fixed in 12.3.1
- Fix · CNA grafana/grafana (Grafana) Fixed in 12.3.1
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
grafana/grafana, grafana/grafana-enterprise 11.6.9, 12.0.8 and 3 more versions
2 records Highest priority Priority MEDIUM 1 MEDIUM, 1 LOW
Other records, highest priority first
- TI-2026-17494 Dashboard Permissions Scope Bypass Enables Cross‑Dashboard Privilege EscalationPriority LOW 38
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
Not affected: 5 products
- Red Hat Ceph Storage 7
- Red Hat Ceph Storage 8
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2026-21720
- 2026-10-03 Alias added: GHSA-m4rj-q4ph-fr4v
References
More Grafana vulnerabilities
- TI-2021-16611 Snapshot authentication bypass in grafana KEVCVSS 3.1CRITICAL 9.8
- TI-2021-19604 Grafana path traversal KEVCVSS 3.1HIGH 7.5
- TI-2024-08600 Grafana SQL Expressions allow for remote code execution CVSS 4.0CRITICAL 9.4
- TI-2023-02931 Authentication bypass by spoofing in Grafana CVSS 3.1CRITICAL 9.8
- TI-2020-10491 The avatar feature in Grafana 3.0.1 through 7.0.1 has an SSRF Incorrect Access Control… CVSS 3.1HIGH 8.2
- TI-2025-03662 Open redirect in Grafana CVSS 3.1HIGH 7.6
Sources
- CVE-2026-21720 · CVE Program
- CVE-2026-21720 · NVD
- FIRST EPSS
- GHSA-m4rj-q4ph-fr4v · GitHub Advisory Database · CC BY 4.0
- CVE-2026-21720 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences