CVE-2026-26931 Elastic CVE debrief

Who should care

Users of Metricbeat, particularly those using versions 8.0.0 to 8.19.13 and 9.0.0 to 9.2.5, should be aware of this vulnerability and take defensive actions to mitigate potential denial of service risks. This includes reviewing deployments, applying patches or updates, and implementing monitoring and compensating controls. Security teams and operators should prioritize this vulnerability due to its potential impact on service availability and overall security posture. Vulnerability management and security teams should ensure that affected systems are identified and remediated promptly.

Technical summary

The CVE-2026-26931 vulnerability in Metricbeat's Prometheus remote_write HTTP handler can lead to denial of service via excessive allocation. This issue, classified as CWE-789, has a CVSS score of 5.7. Affected versions include Metricbeat 8.0.0 to 8.19.13 and 9.0.0 to 9.2.5. The vulnerability allows an attacker to cause excessive allocation, potentially leading to denial of service. Users should review their deployments and apply necessary patches or updates. Monitoring and compensating controls can help limit exposure. The vulnerability does not appear to have been exploited in the wild, but its potential impact should not be underestimated.

Defensive priority

Medium-priority defensive actions are recommended due to the potential for denial of service via excessive allocation.

Recommended defensive actions

• Inventory Metricbeat installations to identify potentially vulnerable versions.
• Apply vendor-provided patches or updates to vulnerable Metricbeat instances.
• Monitor Metricbeat logs for excessive allocation patterns.
• Implement compensating controls to limit exposure.
• Verify Metricbeat configurations for secure Prometheus remote_write handler usage.

Evidence notes

The CVE-2026-26931 vulnerability in Metricbeat's Prometheus remote_write HTTP handler can lead to denial of service via excessive allocation. The vulnerability has a CVSS score of 5.7 and is classified as CWE-789. Affected versions include Metricbeat 8.0.0 to 8.19.13 and 9.0.0 to 9.2.5. Evidence from the CVE Program and NIST NVD detail page supports this assessment. However, the exact scope and impact may vary depending on specific deployments and configurations. Defenders should verify their environments and apply patches or updates accordingly. Limited information is available on potential exploits or attacks, emphasizing the need for vigilance and proactive measures.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.