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CVE-2026-21720

HIGHCVSS 7.5/10EPSS 0.47%

Last modified

CVE-2026-21720 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.47% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.5/10

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

EPSS Probability
0.47%

37.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
GrafanaGrafana>= 3.0.0, < 11.6.9
GrafanaGrafana>= 12.0.0, < 12.0.8
GrafanaGrafana>= 12.1.0, < 12.1.5
GrafanaGrafana>= 12.2.0, < 12.2.3
GrafanaGrafana12.3.0

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is 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.
How severe is CVE-2026-21720?
CVE-2026-21720 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.47% probability of exploitation in the next 30 days.
How do I fix CVE-2026-21720?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-21720?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST