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CVE-2026-21720

7.5 · HIGH

Every uncached /avatar/:hash request spawns a goroutine that refreshes the Gravatar image.

Published Jan 27, 2026CWE-400EPSS 0.70%

Overview

CVE-2026-21720 is a high-severity vulnerability. It was published on January 27, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgrafana.com/security/security-advisories/cve-2026-21720Refaccess.redhat.com/security/cve/CVE-2026-21720Refbugzilla.redhat.com/show_bug.cgi?id=2433226Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21720.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-21720?

CVE-2026-21720 is a high-severity vulnerability. It was published on January 27, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-21720?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-21720?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-21720?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-21720 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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