Critical CVE-2026-23918 Apache HTTP/2 flaw enables DoS, RCE

Executive Summary

CVE-2026-23918 is a critical double-free flaw in Apache HTTP/2 handling that can cause process crashes and service outages. Under specific memory conditions, the same flaw may allow remote code execution in the web server context, leading to compromise.

Key Details

Affected Platform

Attack Surface

Network accessible, unauthenticated

Recommended Action

Apply vendor patch

Affected Environment

Internet-facing Apache HTTP Server 2.4.66 deployments using the HTTP/2 module (mod_http2) are directly exposed. Any organisation relying on Apache for public web services should assume potential impact and verify deployed versions.

Operational Impact

Exposed servers may experience repeated crashes, taking critical web applications and APIs offline until services are restored. If code execution is achieved, attackers could gain control within the web server context, risking broader system and data compromise.

Technical Root Cause

A double-free memory corruption bug exists in HTTP/2 stream handling logic within Apache HTTP Server 2.4.66. Improper memory management allows repeated deallocation of the same memory, creating conditions for crashes or code execution.

Recommended Mitigation

Upgrade Apache HTTP Server from 2.4.66 to 2.4.67 on all affected systems as a priority change.
Where immediate upgrade is not possible, disable mod_http2 and restrict external access to affected services to reduce risk.

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Full Technical Report

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References

Apache HTTP Server security advisory for version 2.4, including details on CVE-2026-23918 and fixed releases. Official CVE entry for CVE-2026-23918 and Apache vendor documentation on upgrading to version 2.4.67.