Vulnerability Report

CVE-2026-21720

Title: Memory Exhaustion in Grafana Avatar Refresh

DoS

Proof Of Concept

No public PoC currently indexed for CVE-2026-21720.

CWE Category NVD-CWE-noinfo

Published Date Jan 27, 2026

Modified Date Jul 15, 2026

Exploit Status Not Found

Score 7.5 CVSS v3.1

Exploit Probability (EPSS)

0.62%

Vulnerability Summary

CVE-2026-21720: 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.

Impacted Vendors

grafana 1

Reference Links

https://grafana.com/security/security-advisories/CVE-2026-21720

CVSS v3.1

Source Entity [email protected]

Severity HIGH

7.5

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

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