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CVE-2026-21720

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

Published: Jan 27, 2026Updated: Jul 15, 2026 Sources: CVE List NVD BDUCWE-400
7.5HIGH
NVD MITRE
EPSS Score
0.6%
Top 53.7%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-400CWE-703CWE-772

Affected Products

Grafana
oss-project·US
grafanaOn-premWeb App
Enterprise Software / itsm-monitoring
grafana/grafana-enterpriseOn-premWeb App
Enterprise Software / itsm-monitoring
grafana/grafanaOn-premWeb App
Enterprise Software / itsm-monitoring
ООО «Ред Софт»
commercial·RUaka red soft
РЕД ОСOn-premOS
Operating Systems / linux-distro
Grafana Labs
commercial·US
GrafanaOn-premWeb App
Enterprise Software / itsm-monitoring

Exploitability

Official Patch Available
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://grafana.com/security/security-advisories/cve-2026-21720
grafana.com
https://access.redhat.com/security/cve/CVE-2026-21720
access.redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2433226
bugzilla.redhat.com
and 4 more references View all →

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