CVE-2026-21720 is a high-severity vulnerability affecting Grafana, with a CVSS score of 7.5. This vulnerability allows memory exhaustion due to the mishandling of goroutines during Gravatar image refresh requests. Attackers can exploit this flaw by sending sustained traffic with random hashes, causing the application to crash under certain conditions. Organizations should prioritize patching immediately to mitigate the risks associated with this vulnerability.
The vulnerability is classified under CWE-400 (Uncontrolled Resource Consumption) and CWE-703 (Improper Handling of Overflow Condition). Grafana's handling of the /avatar/:hash request leads to goroutines blocking indefinitely if they exceed three seconds in a worker queue, ultimately resulting in memory exhaustion and application crashes.
This flaw has been assigned the status of 'Analyzed' and is considered to have high exploitability. Given the nature of the attack vector being network-based, organizations should be prepared for potential exploitation attempts. Notably, there are currently no known public exploits or proofs of concept available for this vulnerability.
Organizations running affected versions of Grafana should take immediate action to address this vulnerability. The urgency of remediation is underscored by the potential impact on availability, as it can lead to service disruptions.
Vulnerability Details
The vulnerability allows for an infinite blocking of goroutines when handling uncached Gravatar image requests. If these requests remain in the worker queue for more than three seconds, the handler times out, leading to goroutines that cannot complete their tasks. This behavior can be exploited through sustained traffic with random hashes, ultimately causing Grafana to exhaust memory.
The CVSS score of 7.5 signifies a high severity level, indicating that organizations must treat this vulnerability with urgency. The vulnerability impacts all versions of Grafana prior to the vendor patch, specifically from versions 3.0.0 to 11.6.9 and certain minor versions of 12.x.
Technical Analysis
The root cause of this vulnerability stems from improper handling of goroutines related to Gravatar image refresh requests. When a request is made, a new goroutine is spawned to handle the refresh process. If this refresh operation takes longer than the allocated time and exceeds the worker queue limit, the goroutine will block indefinitely. This results in an increasing number of blocked goroutines, which can overwhelm system memory.
The attack vector is network-based, meaning that an attacker can exploit this vulnerability remotely without physical access to the system. The attack complexity is low, as it requires no special privileges or user interaction, making it particularly concerning for organizations.
The impacts of this vulnerability are significant. The availability of the Grafana service is at risk, as the exhaustion of memory can lead to service crashes. Confidentiality and integrity impacts are not applicable in this scenario, but the potential for denial of service is a critical concern.
Risk & Impact Analysis
Risk to organizations includes service interruptions due to memory exhaustion, which can affect operational capabilities and user experience. Given the increasing reliance on Grafana for data visualization and monitoring, the blast radius of this vulnerability can be extensive, impacting not just individual users but potentially entire teams relying on Grafana for critical insights.
The urgency of addressing this vulnerability is heightened by the CVSS score of 7.5. Organizations must prioritize remediation efforts to ensure the continued availability of services and protect against potential exploitation attempts.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
Grafana versions from 3.0.0 to 11.6.9 are affected by this vulnerability, as well as specific minor versions of 12.x, particularly those from 12.0.0 to 12.0.8, 12.1.0 to 12.1.5, and 12.2.0 to 12.2.3. Organizations should ensure they are running the latest patched versions to mitigate this risk.
Mitigation & Remediation
Organizations should address this vulnerability by applying the latest patches provided by Grafana. Ensure that you are running a version that is not vulnerable to this issue. Regular updates and monitoring can help prevent similar vulnerabilities in the future. For enhanced security, consider engaging in penetration testing to validate the robustness of your systems.
Detection Guidance
Monitoring for unusual memory usage or application crashes can help identify attempts to exploit this vulnerability. Log indicators such as request patterns to /avatar/:hash can also provide insights into potential abuse. Implementing network signatures to detect sustained traffic with random hashes is advisable.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2026-21720 emphasizes the necessity of robust resource management within applications. As software complexity increases, vulnerabilities related to resource exhaustion are likely to persist. Security teams must prioritize proactive measures and continuous assessment to identify weaknesses in their applications.
This vulnerability also highlights the importance of rigorous testing practices, such as those outlined in the penetration testing methodology, to ensure applications are resilient against various attack vectors.
Organizations should also keep abreast of evolving security trends and vulnerabilities, as these can inform better security practices. Engaging with resources such as the vulnerability management program design can enhance overall security posture.
Additionally, organizations should consider adopting a comprehensive API penetration testing approach to safeguard against evolving threats in their software ecosystem.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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