Grafana Labs 3.0.0 < 11.6.9+security-01 / 12.0.0 < 12.0.8+security-01 / 12.1.0 < 12.1.5+security-01 / 12.2.0 < 12.2.3+security-01 / 12.3.0 < 12.3.1+security-01 DoS (CVE-2026-21720)

high Nessus Plugin ID 297198

Synopsis

The remote host is missing a security update.

Description

The version of Grafana Labs installed on the remote host is affected by a denial of service vulnerability as referenced in the CVE-2026-21720 advisory.

- 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. (CVE-2026-21720)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update Grafana Labs to 11.6.9+security-01, 12.0.8+security-01, 12.1.5+security-01, 12.2.3+security-01, 12.3.1+security-01 or later.

Plugin Details

Severity: High

ID: 297198

File Name: grafana_CVE-2026-21720.nasl

Version: 1.1

Type: remote

Family: Web Servers

Published: 1/30/2026

Updated: 1/30/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: High

Base Score: 7.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C

CVSS Score Source: CVE-2026-21720

CVSS v3

Risk Factor: High

Base Score: 7.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vulnerability Information

CPE: cpe:/a:grafana:grafana

Patch Publication Date: 1/27/2026

Vulnerability Publication Date: 1/27/2026

Reference Information

CVE: CVE-2026-21720

IAVB: 2026-B-0025

Detections

Analytics