Bug 2433226 (CVE-2026-21720)

Summary:	CVE-2026-21720 grafana: Grafana: Denial of Service via resource exhaustion from avatar requests
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	amctagga, aoconnor, bniver, flucifre, gmeno, groman, lchilton, mbenjamin, mhackett, sfeifer, sostapov, vereddy
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
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Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in Grafana. A remote attacker can exploit this vulnerability by sending a sustained volume of uncached /avatar/:hash requests. This action causes the system to create and block goroutines, which are lightweight concurrent functions, leading to a continuous increase in memory usage. Over time, this resource exhaustion can cause Grafana to crash, resulting in a Denial of Service (DoS).	Story Points:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-01-27 10:01:37 UTC

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.