mod_proxy Malformed FTP Command Denial of Service
Severe, but no confirmed exploitation yet. Schedule remediation in your next patch cycle and apply mitigations if you're exposed.
An unauthenticated attacker, remotely over the network, can fully compromise the system — steal data, tamper with it and take it offline.
mod_proxy in Apache 1.2.5 and earlier allows remote attackers to cause a denial of service via malformed FTP commands, which causes Apache to dump core.
Inferred from the weakness type (CWE) and how the flaw is reached — the techniques an attacker would chain to exploit this. Real-world corroboration appears here as threat intel is folded in.
Generated by Wavense from the CVE record — an immediate mitigation and the permanent fix.
To reduce immediate risk, restrict network access to the Apache server's mod_proxy service to only trusted internal networks or specific IP addresses using firewall rules. Deploy an Intrusion Detection System (IDS) to monitor for and alert on unusual or malformed FTP command patterns directed at the server. Consider placing a reverse proxy or load balancer in front to filter potentially malicious traffic.
The permanent resolution requires upgrading all affected Apache HTTP Server instances running mod_proxy to a version newer than 1.2.5. Consult official Apache HTTP Server security advisories and documentation to identify the latest stable and patched release that addresses this and other known vulnerabilities. Ensure the upgrade process follows best practices for configuration and testing.
Remote attackers can exploit this vulnerability by sending specially crafted malformed FTP commands to the mod_proxy module. This action causes the Apache web server to crash unexpectedly, resulting in a core dump and a complete denial of service for all legitimate users. The direct consequence is severe operational disruption and unavailability of hosted web services.
No CWE classification has been assigned.
Other CVEs affecting http server
Vulnerability in the Oracle HTTP Server, Oracle Weblogic Server Proxy Plug-in product of Oracle Fusion Middleware (component: Weblogic Server Proxy Plug-in for Apache HTTP Server, Weblogic Server Proxy Plug-in for IIS). Supported versions that are affected are 12.2.1.4.0, 14.1.1.0.0 and 14.1.2.0.0. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP to compromise Oracle HTTP Server, Oracle Weblogic Server Proxy Plug-in. While the vulnerability is in Oracle HTTP Server, Oracle Weblogic Server Proxy Plug-in, attacks may significantly impact additional products (scope change). Successful attacks of this vulnerability can result in unauthorized creation, deletion or modification access to critical data or all Oracle HTTP Server, Oracle Weblogic Server Proxy Plug-in accessible data as well as unauthorized access to critical data or complete access to all Oracle HTTP Server, Oracle Weblogic Server Proxy Plug-in accessible data. Note: Affected version for Weblogic Server Proxy Plug-in for IIS is 12.2.1.4.0 only. CVSS 3.1 Base Score 10.0 (Confidentiality and Integrity impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N).
It 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.
A 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.
Improper escaping of output in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows an attacker to map URLs to filesystem locations that are permitted to be served by the server but are not intentionally/directly reachable by any URL, resulting in code execution or source code disclosure. Substitutions in server context that use a backreferences or variables as the first segment of the substitution are affected. Some unsafe RewiteRules will be broken by this change and the rewrite flag "UnsafePrefixStat" can be used to opt back in once ensuring the substitution is appropriately constrained.
A local privilege escalation vulnerability was found on polkit's pkexec utility. The pkexec application is a setuid tool designed to allow unprivileged users to run commands as privileged users according predefined policies. The current version of pkexec doesn't handle the calling parameters count correctly and ends trying to execute environment variables as commands. An attacker can leverage this by crafting environment variables in such a way it'll induce pkexec to execute arbitrary code. When successfully executed the attack can cause a local privilege escalation given unprivileged users administrative rights on the target machine.
In Apache HTTP Server 2.4 releases 2.4.17 to 2.4.38, with MPM event, worker or prefork, code executing in less-privileged child processes or threads (including scripts executed by an in-process scripting interpreter) could execute arbitrary code with the privileges of the parent process (usually root) by manipulating the scoreboard. Non-Unix systems are not affected.
Vulnerability in the Oracle Weblogic Server Proxy Plug-in product of Oracle Fusion Middleware (component: WebLogic Server Proxy Plug-In for Third-Party Web Servers). The supported version that is affected is 15.1.1.0.0. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP to compromise Oracle Weblogic Server Proxy Plug-in. While the vulnerability is in Oracle Weblogic Server Proxy Plug-in, attacks may significantly impact additional products (scope change). Successful attacks of this vulnerability can result in unauthorized creation, deletion or modification access to critical data or all Oracle Weblogic Server Proxy Plug-in accessible data as well as unauthorized access to critical data or complete access to all Oracle Weblogic Server Proxy Plug-in accessible data. CVSS 3.1 Base Score 10.0 (Confidentiality and Integrity impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N).