CVE-2026-78594 Elastic CVE debrief

Who should care

APM Server administrators, Elastic customers using APM Server, security teams responsible for monitoring and protecting against denial of service attacks, and operators managing affected product deployments should review and act on this vulnerability. Compensating controls should be implemented to detect and prevent highly compressed data storage, and APM Server should be regularly updated to the latest version. Monitoring and detection capabilities should be reviewed to ensure visibility into potential exploitation attempts. Asset inventory and vulnerability management processes should also be updated to account for this vulnerability. Rollback and change window procedures should be considered for remediation efforts. Source tracking and logging mechanisms should be evaluated for potential improvements in detecting and responding to exploitation attempts. Security teams should coordinate with affected teams to ensure proper mitigation and remediation efforts are in place. This may involve reviewing and updating incident response plans and procedures to address potential exploitation of this vulnerability. Additionally, affected product deployments should be prioritized for remediation based on their criticality and potential impact on business operations. Communication with stakeholders, including customers and partners, may be necessary to ensure transparency and trust. Finally, lessons learned from this incident should be documented and used to improve future vulnerability management and incident response efforts. The goal is to minimize potential impact and ensure the security and integrity of affected systems and data. This requires a coordinated effort from various teams and stakeholders to ensure effective mitigation and remediation of the vulnerability. By taking these steps, organizations can reduce the risk associated with this vulnerability and protect their systems and data from potential exploitation. It is essential to stay informed about the latest developments and updates related to this vulnerability and to be prepared to respond quickly and effectively in the event of an incident. This includes staying up-to-date with the latest security advis

Technical summary

CVE-2026-78594 is a vulnerability in Elastic's APM Server, classified under CWE-409, Improper Handling of Highly Compressed Data. An authenticated user with write access to source map content can store specially crafted, highly compressed content that, when processed, exhausts the memory available to APM Server, leading to a persistent denial of service. The vulnerability has a CVSS score of 4.9 and is considered medium severity.

Defensive priority

Authenticated users with write access to source map content could exploit this vulnerability, leading to a denial of service. Immediate attention is advised for APM Server administrators.

Recommended defensive actions

• Review and limit write access to source map content
• Monitor APM Server for unusual memory usage patterns
• Implement compensating controls to detect and prevent highly compressed data storage
• Regularly update APM Server to the latest version
• Remove any stored malicious content

Evidence notes

The CVE-2026-78594 record indicates that APM Server is vulnerable to a denial of service via excessive allocation when processing highly compressed data. Authenticated users with write access to source map content can store maliciously crafted content that exhausts available memory upon processing, causing the server to terminate. This condition persists across restarts until the stored content is removed. The vulnerability is classified under CWE-409 and has a CVSS score of 4.9.

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.