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Vulnerability record · CVE-2026-21720 · published 27 January 2026

CVE-2026-21720: Grafana uncontrolled resource consumption vulnerability

Grafana · Grafana

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.

7.5 CVSS 3.1 High EPSS 0.70% · top 48.7% CWE-400 · Uncontrolled resource consumptionCWE-703 · CWE-703
7.5CVSS 3.1 base score
0.70%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
15 Jul 2026Last modified by NVD

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://grafana.com/security/security-advisories/cve-2026-21720 Broken Link
https://access.redhat.com/security/cve/CVE-2026-21720
https://bugzilla.redhat.com/show_bug.cgi?id=2433226
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21720.json

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Source: NIST National Vulnerability Database (record CVE-2026-21720), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.