high CVSS 7.5

CVE-2025-53020·Apache vulnerability

Late Release of Memory after Effective Lifetime vulnerability in Apache HTTP Server. This issue affects Apache HTTP Server: from 2.4.17 up to 2.4.63. Users are recommended to upgrade to version 2.4.64, which fixes the issue.

Severity
high
Software
Apache
Fixed in
2.4.64
Published
2025-07-10

Affected versions

From: 2.4.17

Until: 2.4.64

Fixed in: 2.4.64

How to fix this CVE

Apache HTTP Server versions 2.4.17 through 2.4.63 contain a use-after-free memory management flaw that can trigger denial-of-service conditions on affected web servers. Immediately upgrade to Apache 2.4.64 or later to eliminate this vulnerability and restore normal server availability. Verify the upgrade is complete by checking the version output and monitoring server logs for any residual memory-related errors.

sudo dnf update httpd

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Run `apache2 -v` (or `httpd -v` on RHEL/CentOS) and confirm the version number is between 2.4.17 and 2.4.63
  2. Step 2: Check the Apache configuration for any exposed modules or listeners by examining `/etc/apache2/apache2.conf` and enabled sites in `/etc/apache2/sites-enabled/`
  3. Step 3: Search Apache error logs with `grep -i 'segmentation\|memory\|fault' /var/log/apache2/error.log` to identify crash signatures
  4. Step 4: After upgrading, run `apache2 -v` or `httpd -v` again to confirm version is 2.4.64 or higher, then restart the service with `sudo systemctl restart apache2`

FAQ

What is CVE-2025-53020?

CVE-2025-53020 is a use-after-free memory vulnerability in Apache HTTP Server that occurs when memory is incorrectly deallocated before the end of its intended lifetime. This flaw allows remote attackers to trigger denial-of-service conditions by causing the server process to crash.

Is CVE-2025-53020 being actively exploited?

No, CVE-2025-53020 is not currently listed as actively exploited according to CISA's Known Exploited Vulnerabilities catalog, and no public exploit code is available.

What versions of Apache are affected by CVE-2025-53020?

Apache HTTP Server versions 2.4.17 through 2.4.63 are vulnerable. Version 2.4.64 and all subsequent releases include the fix.

How do I check if my server is vulnerable to CVE-2025-53020?

Run `apache2 -v` or `httpd -v` depending on your system. If the version output shows 2.4.17 to 2.4.63, your server is vulnerable and requires immediate upgrading.

Does Defensia detect CVE-2025-53020?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Apache is installed on a monitored server, CVE-2025-53020 will appear in your dashboard with remediation steps.

Related Apache CVEs

CVE-2021-41773CVSS 10A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. An attacker could use a path traversal attack to map URLs to files outside the directories configured by Alias-like directives. If files outside of these directories are not protected by the usual default configuration "require all denied", these requests can succeed. If CGI scripts are also enabled for these aliased pathes, this could allow for remote code execution. This issue is known to be exploited in the wild. This issue only affects Apache 2.4.49 and not earlier versions. The fix in Apache HTTP Server 2.4.50 was found to be incomplete, see CVE-2021-42013.
CVE-2021-42013CVSS 10It was found that the fix for CVE-2021-41773 in Apache HTTP Server 2.4.50 was insufficient. An attacker could use a path traversal attack to map URLs to files outside the directories configured by Alias-like directives. If files outside of these directories are not protected by the usual default configuration "require all denied", these requests can succeed. If CGI scripts are also enabled for these aliased pathes, this could allow for remote code execution. This issue only affects Apache 2.4.49 and Apache 2.4.50 and not earlier versions.
CVE-2026-59797CVSS 9.8Improper Privilege Management vulnerability in Apache HTTP Server's mod_ssl via SSLRequire and file-related expressions. This issue affects Apache HTTP Server: from 2.4.0 through 2.4.68.
CVE-2024-38476CVSS 9.8Vulnerability in core of Apache HTTP Server 2.4.59 and earlier are vulnerably to information disclosure, SSRF or local script execution via backend applications whose response headers are malicious or exploitable. Users are recommended to upgrade to version 2.4.60, which fixes this issue.
CVE-2026-28780CVSS 9.8Heap-based Buffer Overflow vulnerability in mod_proxy_ajp of Apache HTTP Server. If mod_proxy_ajp connects to a malicious AJP server this AJP server can send a malicious AJP message back to mod_proxy_ajp and cause it to write 4 attacker controlled bytes after the end of a heap based buffer. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

References

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