CVE-2026-54399: Apache HttpComponents Core: Unbounded HTTP Header/Line Length in Default Configuration
Uncontrolled Resource Consumption vulnerability in the HTTP/1.1 message parser in Apache HttpComponents Core (5.4.2 and earlier, 5.5-beta1 and earlier) allows an remote attacker to cause a denial of service through memory exhaustion by sending messages with excessive number of headers / excessive header length
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Apache HttpComponents Coreto a version that resolves this vulnerability.Fixed in 5.4.2 - Upgrade
Upgrade
Apache HttpComponents Coreto a version that resolves this vulnerability.Fixed in 5.5-beta1 - Upgrade
Upgrade
Apache HttpComponents Coreto a version that resolves this vulnerability.Fixed in 5.4.2 and earlier, 5.5-beta1 and earlier - Compensating control
Add a compensating control by limiting incoming HTTP header count and header/line sizes at the reverse proxy/load balancer/WAF to prevent memory exhaustion via excessive headers or header length.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-54399?
The severity of CVE-2026-54399 is high with a CVSS score of 7.5.
How do I fix CVE-2026-54399?
To fix CVE-2026-54399, upgrade Apache HttpComponents Core to version 5.4.3 or later.
What type of vulnerability is CVE-2026-54399?
CVE-2026-54399 is a denial of service vulnerability due to unbounded HTTP header/line lengths in the default configuration.
Which versions of Apache HttpComponents Core are affected by CVE-2026-54399?
Versions 5.4.2 and earlier, as well as 5.5-beta1 and earlier, are affected by CVE-2026-54399.
What can exploitation of CVE-2026-54399 lead to?
Exploitation of CVE-2026-54399 can lead to memory exhaustion and consequent denial of service.