CVE-2021-40438 remediation guide

Identify the affected asset

Confirm whether Apache Software Foundation Apache HTTP Server, rocky linux, enterprise linux is installed, record the deployed version and installation path, and identify exposed interfaces.

• Record the product name, package or appliance identifier, and installed version.
• Identify internet-facing, administrative, API, and internal access paths.
• Preserve the pre-change configuration and relevant service logs.

Validate the affected-version match

Compare the deployed version with the affected range: >= Apache HTTP Server 2.4 <= 2.4.48, 8.0, 8.1, 8.2, 8.4, 8.6, 8.8, 7.0 s390x, 7.0, 7.2, 7.3, 7.4, 7.6, 7.7, 1.0, <= 2.4.48, 34, 35, 9.0, 10.0. Treat incomplete inventory results as unresolved.

Prioritize with independent signals

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog. Combine this signal with asset criticality, exposure, compensating controls, and business impact.

Apply supported remediation

Apply updates per vendor instructions.

Verify the result

Confirm the resulting version, service health, authentication and access paths, monitoring coverage, and relevant security logs.

• Confirm the expected version and package state.
• Run a functional health check for critical service paths.
• Review authentication, error, application, and security monitoring logs.
• Reassess exposure if the supported fix cannot be applied.