CVE-2026-21720Network attack vectorHinoki check available

Unauthenticated service crash via avatar goroutine leak

Published Jan 27, 2026 · Updated Jan 27, 2026

Denial of service in affected Grafana and Grafana Enterprise releases allows remote attackers to crash the server via avatar requests. An uncached /avatar/:hash request starts a refresh goroutine that blocks on an unbuffered result channel when the 10-slot queue exceeds the three-second handler timeout. No authentication or user interaction is required; sustained requests using random hashes grow memory use until the Grafana process crashes on affected systems.

CVSS severity7.5
High
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
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Summary

What happened

Denial of service in affected Grafana and Grafana Enterprise releases allows remote attackers to crash the server via avatar requests. An uncached /avatar/:hash request starts a refresh goroutine that blocks on an unbuffered result channel when the 10-slot queue exceeds the three-second handler timeout. No authentication or user interaction is required; sustained requests using random hashes grow memory use until the Grafana process crashes on affected systems.

The record

CVE
CVE-2026-21720
Published
Jan 27, 2026
Updated
Jan 27, 2026
Vendor
Grafana Labs
Product
Grafana
Classifications
CWE-772, CWE-703, CWE-400, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.0.0 <11.6.9
  2. Affected versionversion=3.0.0 <12.0.8
  3. Affected versionversion=3.0.0 <12.1.5
  4. Affected versionversion=3.0.0 <12.2.3
  5. Affected versionversion=3.0.0 <12.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Grafana Labs · Grafanaversion=3.0.0 <11.6.9; version=3.0.0 <12.0.8; version=3.0.0 <12.1.5; version=3.0.0 <12.2.3; version=3.0.0 <12.3.1
Grafana Labs · Grafana Enterpriseversion=3.0.0 <11.6.9; version=3.0.0 <12.0.8; version=3.0.0 <12.1.5; version=3.0.0 <12.2.3; version=3.0.0 <12.3.1

Published CVSS scores

7.5redhat-SADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Grafana LabsCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-772Missing Release of Resource after Effective Lifetime
CWE-703Improper Check or Handling of Exceptional Conditions
CWE-400Uncontrolled Resource Consumption
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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