CVE-2026-73636
Received Received - Intake

Authentication Bypass via Replay in Apache HTTP Server

Publication date: 2026-10-01

Last updated on: 2026-10-01

Assigner: Apache Software Foundation

Description
Authentication bypass by capture-replay in mod_auth_digest in Apache Software Foundation Apache HTTP Server 2.4.x on all platforms allows a man-in-the-middle (MITM) attacker to replay captured digest authentication credentials via crafted requests that trigger garbage collection of the client's shared memory entry when AuthDigestNonceLifetime is set to 0. Users are recommended to upgrade to version 2.4.69, which fixes this issue.

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Meta Information

Published
2026-10-01
Last Modified
2026-10-01
Generated
2026-10-01
AI Q&A
2026-10-01
EPSS Evaluated
N/A
NVD
CVE-2026-73636
EUVD
EUVD-2026-90907

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
apache_software_foundation apache_http_server 2.4.69

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-294 A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).

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Executive Summary

This vulnerability is an authentication bypass issue in Apache HTTP Server's mod_auth_digest module. It allows a man-in-the-middle attacker to replay captured digest authentication credentials by exploiting crafted requests that trigger garbage collection of a client's shared memory entry when AuthDigestNonceLifetime is set to 0.

Detection Guidance

This vulnerability can be detected by checking the Apache HTTP Server version. If the version is 2.4.x and AuthDigestNonceLifetime is set to 0, the system may be vulnerable. Run: httpd -v to check the version and grep AuthDigestNonceLifetime /path/to/httpd.conf to verify the setting.

Impact Analysis

An attacker could gain unauthorized access to protected resources by replaying stolen authentication credentials. This could lead to data breaches, unauthorized actions, or further network compromise depending on the server's configuration and permissions.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating compliance requirements such as GDPR's data protection principles or HIPAA's security rules. Organizations may face legal penalties, reputational damage, and loss of trust if exploited.

Mitigation Strategies

Upgrade Apache HTTP Server to version 2.4.69 or later. If upgrading is not immediately possible, set AuthDigestNonceLifetime to a non-zero value to prevent garbage collection issues.

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