Actively exploited in the wild
Apache HTTP Server Improper Escaping of Output Vulnerability
Apache - HTTP Server · Listed in the CISA KEV since 2025-05-01. This indicates confirmed attacks in production environments.
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CVE-2024-38475
CriticalCVSS 9.1KEVSummary
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 but not directly reachable, leading to code execution or source code disclosure.
Risk Assessment
An attacker can access sensitive files or execute arbitrary code on the server, potentially leading to server compromise and data leakage.
Recommendation
Immediately upgrade Apache HTTP Server to version 2.4.60 or later, which includes a fix for this vulnerability.
Other vulnerabilities in Apache HTTP Server
See all- CVE-2017-9798High
Apache httpd allows remote attackers to read secret data from process memory if the Limit directive can be set in a user's .htaccess file, or if httpd.conf has certain misconfigurations. This affects the Apache HTTP Server through 2.2.34 and 2.4.x through 2.4.27.
- CVE-2016-8743High
Apache HTTP Server, in all releases prior to 2.2.32 and 2.4.25, was liberal in the whitespace accepted from requests and sent in response lines and headers. This acceptance of different behaviors represented a security concern when httpd participates in any chain of proxies or interacts with back-end application servers.
- CVE-2016-5387High
Apache HTTP Server through 2.4.23 does not protect applications from untrusted client data in the HTTP_PROXY environment variable, allowing remote attackers to redirect an application's outbound HTTP traffic to an arbitrary proxy server via a crafted Proxy header in an HTTP request.
- CVE-2016-4979High
Apache HTTP Server versions 2.4.18 to 2.4.20, when mod_http2 and mod_ssl are enabled, improperly recognize the 'SSLVerifyClient require' directive for HTTP/2 request authorization. This allows remote attackers to bypass intended access restrictions.
- CVE-2024-40725Medium
A partial fix for CVE-2024-39884 in Apache HTTP Server 2.4.61 ignores some legacy content-type based configurations like AddType. Under certain circumstances with indirect file requests, this can lead to source code disclosure of local content.
- CVE-2024-36387Medium
Serving WebSocket protocol upgrades over an HTTP/2 connection could result in a Null Pointer dereference, leading to a crash of the server process, degrading performance.
- CVE-2024-38477Medium
Null pointer dereference in mod_proxy in Apache HTTP Server 2.4.59 and earlier allows an attacker to crash the server via a malicious request.
- CVE-2023-38709Medium
Faulty input validation in the core of Apache HTTP Server through 2.4.58 allows malicious or exploitable backend/content generators to split HTTP responses, leading to HTTP response splitting attacks.
- CVE-2024-24795Medium
HTTP Response splitting in multiple modules in Apache HTTP Server allows an attacker that can inject malicious response headers into backend applications to cause an HTTP desynchronization attack.
- CVE-2024-27316Medium
HTTP/2 incoming headers exceeding the limit are temporarily buffered in nghttp2 to generate an informative HTTP 413 response. If a client does not stop sending headers, this leads to memory exhaustion.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

