Unauthenticated DoS: avatar cache leaks goroutines when /avatar/:hash requests time out

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Summary

CVECVE-2026-21720
StatePUBLISHED
AssignerGRAFANA
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-27 09:15:48 UTC
Updated2026-06-30 03:17:24 UTC
DescriptionEvery 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-400 | CWE-703 | CWE-772 | CWE-400 CWE-400 Uncontrolled Resource Consumption | CWE-703 CWE-703 Improper Check or Handling of Exceptional Conditions | CWE-772 Missing Release of Resource after Effective Lifetime

VersionSourceTypeScoreSeverityVector
3.1ADPCVSS7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.10b0ca135-0b70-47e7-9f44-1890c2a1c46cSecondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Grafana Grafana All All All All
Application Grafana Grafana All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Grafana Grafana/grafana-enterprise affected 3.0.0 11.6.9 semver Not specified
CNA Grafana Grafana/grafana-enterprise affected 3.0.0 12.0.8 semver Not specified
CNA Grafana Grafana/grafana-enterprise affected 3.0.0 12.1.5 semver Not specified
CNA Grafana Grafana/grafana affected 3.0.0 11.6.9 semver Not specified
CNA Grafana Grafana/grafana affected 3.0.0 12.0.8 semver Not specified
CNA Grafana Grafana/grafana affected 3.0.0 12.1.5 semver Not specified
CNA Grafana Grafana/grafana-enterprise affected 3.0.0 12.2.3 semver Not specified
CNA Grafana Grafana/grafana affected 3.0.0 12.2.3 semver Not specified
CNA Grafana Grafana/grafana-enterprise affected 3.0.0 12.3.1 semver Not specified
CNA Grafana Grafana/grafana affected 3.0.0 12.3.1 semver Not specified
ADP Red Hat Red Hat Ceph Storage 7 Not specified Not specified
ADP Red Hat Red Hat Ceph Storage 8 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 10 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 8 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 9 Not specified Not specified

References

ReferenceSourceLinkTags
access.redhat.com/security/cve/CVE-2026-21720 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
grafana.com/security/security-advisories/cve-2026-21720 [email protected] grafana.com Broken Link
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21720.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c security.access.redhat.com
bugzilla.redhat.com/show_bug.cgi 0b0ca135-0b70-47e7-9f44-1890c2a1c46c bugzilla.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
ADP2026-01-27T10:01:10.677ZReported to Red Hat.
ADP2026-01-27T09:07:04.758ZMade public.
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