CVE-2001-1072 in HTTP Server
Summary
by MITRE
Apache with mod_rewrite enabled on most UNIX systems allows remote attackers to bypass RewriteRules by inserting extra / (slash) characters into the requested path, which causes the regular expression in the RewriteRule to fail.
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Analysis
by VulDB Data Team • 09/29/2025
The vulnerability described in CVE-2001-1072 represents a significant security flaw in the Apache HTTP Server when configured with the mod_rewrite module on unix-based systems. This issue stems from how the web server processes URL paths containing excessive forward slashes, creating a potential bypass mechanism for access controls and security policies implemented through rewrite rules. The vulnerability specifically affects systems where mod_rewrite is enabled and configured to handle URL rewrites, making it particularly relevant to web applications that rely on URL manipulation for security enforcement.
The technical root cause of this vulnerability lies in the improper handling of multiple consecutive slash characters within URL paths. When an attacker crafts a request containing extra slash characters in the requested path, the Apache server's mod_rewrite module fails to properly normalize these paths before applying regular expression matching in RewriteRule directives. This path normalization failure occurs because the server treats multiple slashes as separate path components rather than collapsing them into a single component, effectively allowing the attacker to manipulate the URL parsing logic. The flaw manifests as a regular expression matching failure where the intended rewrite rules do not properly match against the manipulated path, thereby bypassing the security controls that were designed to protect specific resources or enforce access restrictions.
The operational impact of this vulnerability extends beyond simple path manipulation, as it can enable attackers to circumvent various security measures that depend on mod_rewrite for access control enforcement. Attackers can exploit this weakness to bypass authentication mechanisms, access restricted directories, or circumvent URL-based security policies that rely on proper path normalization. This vulnerability particularly affects web applications that implement security through URL rewriting, such as those using rewrite rules to protect sensitive resources or enforce directory access controls. The bypass capability means that even properly configured rewrite rules may become ineffective against this specific attack vector, potentially exposing sensitive application functionality to unauthorized access.
Security professionals should note that this vulnerability aligns with CWE-177, which describes the weakness of improper handling of multiple slashes in path names, and relates to the broader category of path traversal vulnerabilities. The attack pattern associated with CVE-2001-1072 follows the techniques outlined in the ATT&CK framework under the T1072 category for "Path Interception" and related privilege escalation methods. Organizations should implement immediate mitigations including updating to patched versions of Apache HTTP Server, configuring proper path normalization rules, and implementing additional security layers such as web application firewalls to detect and block malformed URL requests. Regular security assessments should verify that rewrite rules properly handle edge cases including multiple consecutive slashes and that access control mechanisms remain effective against such path manipulation attacks.