EUVD-2025-21015
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
4Description
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.
Analysis
CVE-2025-53020 is a late release of memory after effective lifetime vulnerability (use-after-free) in Apache HTTP Server versions 2.4.17 through 2.4.63 that allows unauthenticated remote attackers to cause denial of service with high availability impact. The vulnerability has a CVSS score of 7.5 (high severity) with network-accessible attack vector and low attack complexity, making it easily exploitable without authentication. Affected organizations running vulnerable Apache HTTP Server versions should prioritize upgrading to version 2.4.64 immediately.
Technical Context
This vulnerability stems from CWE-401 (Missing Release of Memory after Effective Lifetime), a memory management flaw where the Apache HTTP Server fails to properly deallocate memory objects after their intended use ends. This use-after-free condition occurs during the effective processing lifetime of requests or connections handled by the web server. The affected product is Apache HTTP Server (CPE: cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*), a widely-deployed open-source web server used in mission-critical infrastructure. The flaw likely exists in core request processing, memory pooling, or connection handling routines that manage the lifecycle of internal data structures. Memory corruption resulting from use-after-free can lead to crashes, heap corruption, and potential information disclosure, though this CVE specifically manifests as a denial of service vector.
Affected Products
Apache HTTP Server versions 2.4.17, 2.4.18, 2.4.19, 2.4.20, 2.4.21, 2.4.22, 2.4.23, 2.4.25, 2.4.26, 2.4.27, 2.4.28, 2.4.29, 2.4.37, 2.4.38, 2.4.39, 2.4.40, 2.4.41, 2.4.43, 2.4.46, 2.4.48, 2.4.49, 2.4.50, 2.4.51, 2.4.52, 2.4.53, 2.4.54, 2.4.55, 2.4.56, 2.4.57, 2.4.58, 2.4.59, 2.4.60, 2.4.61, 2.4.62, and 2.4.63 are vulnerable. This includes all minor versions from 2.4.17 through 2.4.63 inclusive. Affected systems running on any operating system where Apache HTTP Server 2.4.x is deployed (Linux, Windows, BSD, etc.) are impacted. Organizations should identify all instances via asset inventory, network scanning, and service enumeration to determine exposure scope.
Remediation
IMMEDIATE ACTION: Upgrade Apache HTTP Server to version 2.4.64 or later. This is the patched version that resolves CVE-2025-53020. Organizations should: (1) Test the 2.4.64 upgrade in non-production environments first to ensure compatibility with loaded modules, custom configurations, and applications; (2) Plan a phased rollout across production systems, prioritizing internet-facing servers; (3) Implement maintenance windows or use load balancing to avoid service interruption; (4) Verify successful patch installation by confirming version output and reviewing server logs for errors. TEMPORARY MITIGATION (while patching): Deploy rate-limiting and connection throttling to reduce denial-of-service attack surface; implement WAF/IDS signatures to detect potential exploitation patterns; restrict access to the HTTP server to trusted networks if operationally feasible. Workarounds are limited due to the in-process nature of the vulnerability. Complete patching is the only reliable remediation.
Priority Score
Vendor Status
Ubuntu
Priority: Medium| Release | Status | Version |
|---|---|---|
| upstream | released | 2.4.64-1 |
| jammy | released | 2.4.52-1ubuntu4.15 |
| noble | released | 2.4.58-1ubuntu8.7 |
| plucky | released | 2.4.63-1ubuntu1.1 |
| trusty | not-affected | - |
| bionic | released | 2.4.29-1ubuntu4.27+esm6 |
| focal | released | 2.4.41-4ubuntu3.23+esm2 |
| xenial | released | 2.4.18-2ubuntu3.17+esm16 |
Debian
| Release | Status | Fixed Version | Urgency |
|---|---|---|---|
| bullseye | fixed | 2.4.65-1~deb11u1 | - |
| bullseye (security) | fixed | 2.4.66-1~deb11u1 | - |
| bookworm | fixed | 2.4.65-1~deb12u1 | - |
| bookworm (security) | vulnerable | 2.4.62-1~deb12u2 | - |
| trixie | fixed | 2.4.66-1~deb13u2 | - |
| forky, sid | fixed | 2.4.66-8 | - |
| (unstable) | fixed | 2.4.64-1 | - |
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External POC / Exploit Code
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