CVE-2025-53020: 
Apache HTTP Server vulnerability analysis and mitigation

A Late Release of Memory after Effective Lifetime vulnerability was discovered in Apache HTTP Server (CVE-2025-53020). The vulnerability affects Apache HTTP Server versions from 2.4.17 up to 2.4.63, and was disclosed on July 10, 2025. The issue is specifically related to HTTP/2 DoS by Memory Increase, impacting the server's memory management (Apache Httpd).

The vulnerability is classified with a CVSS v3.1 Base Score of 7.5 (HIGH) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. The issue is identified as CWE-401 (Missing Release of Memory after Effective Lifetime). The vulnerability specifically affects the HTTP/2 implementation in the server, where memory is not properly released after its effective lifetime (NVD, Ubuntu).

The vulnerability can lead to memory exhaustion in the Apache HTTP Server, potentially resulting in a denial of service condition. The CVSS scoring indicates that while there is no impact on confidentiality or integrity, there is a high impact on availability (NVD).

Users are recommended to upgrade to Apache HTTP Server version 2.4.64, which contains the fix for this vulnerability. The issue has been patched in various Linux distributions, with Ubuntu providing fixed packages for affected versions (Apache Httpd, Ubuntu).

The vulnerability was discovered and reported by Gal Bar Nahum, with the fix being developed on June 19, 2025, and released on July 10, 2025. The issue was treated as a moderate severity vulnerability by the Apache HTTP Server project (Apache Httpd).