CVE-2026-21720: Unauthenticated DoS: avatar cache leaks goroutines when /avatar/:hash requests time out
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.
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Tracked companies
Mapped from the CVE’s affected-product data, NVD CPE matches, vendor advisories or package feeds. A mapping means the vendor’s software is named, not that its hosted service was exposed.
Status incidents that name it
No tracked status incident names this CVE.
Affected vendors and products
Grafana: grafana/grafanaGrafana: grafana/grafana-enterpriseRed Hat: Red Hat Ceph Storage 7Red Hat: Red Hat Ceph Storage 8Red Hat: Red Hat Enterprise Linux 10Red Hat: Red Hat Enterprise Linux 8Red Hat: Red Hat Enterprise Linux 9
References
- CVE record on cve.org (opens in new tab)
- NVD entry (opens in new tab)
- grafana.com/security/security-advisories/cve-2026-21720 (opens in new tab)
- CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (opens in new tab)
- This product uses data from the NVD API but is not endorsed or certified by the NVD. (opens in new tab)
- Known Exploited Vulnerabilities catalog from CISA. (opens in new tab)
- EPSS scores from FIRST (Exploit Prediction Scoring System). (opens in new tab)