CVE-2022-30556: Apache HTTP Server Information Disclosure

CVE-2022-30556 Overview

CVE-2022-30556 is an information disclosure vulnerability affecting Apache HTTP Server versions 2.4.53 and earlier. The flaw exists in the r:wsread() function, which may return length values to calling applications that point past the end of the storage allocated for the buffer. This out-of-bounds read condition can allow attackers to potentially access sensitive information stored in adjacent memory regions.

Critical Impact
Remote attackers can exploit this vulnerability over the network without authentication to potentially disclose sensitive information from server memory, compromising confidentiality.

Affected Products

Apache HTTP Server versions up to and including 2.4.53
NetApp Clustered Data ONTAP
Fedora 35 and Fedora 36

Discovery Timeline

June 8, 2022 - Vulnerability disclosed via Openwall OSS-Security Message
June 9, 2022 - CVE-2022-30556 published to NVD
May 1, 2025 - Last updated in NVD database

Technical Details for CVE-2022-30556

Vulnerability Analysis

This vulnerability is classified as CWE-200 (Information Exposure) and represents an out-of-bounds read condition in Apache HTTP Server. The core issue lies in the r:wsread() function, which is used by applications to read data from the request. When this function is called, it may return a length value that extends beyond the actual allocated buffer boundaries.

The vulnerability can be exploited remotely over the network with low attack complexity. No privileges or user interaction are required for exploitation, making it accessible to unauthenticated attackers. While the vulnerability does not allow an attacker to modify data or cause denial of service, it poses a significant risk to confidentiality as it could expose sensitive data from server memory.

Root Cause

The root cause of CVE-2022-30556 is improper bounds checking in the r:wsread() function within Apache HTTP Server. The function fails to properly validate that the returned length value stays within the boundaries of the allocated buffer storage. This allows applications calling the function to receive length values that reference memory beyond the intended buffer, potentially exposing adjacent memory contents.

Attack Vector

The attack vector for this vulnerability is network-based. An attacker can exploit this vulnerability by sending specially crafted requests to an affected Apache HTTP Server instance. The server's r:wsread() function may then return incorrect length values that point past the allocated buffer, allowing the attacker to potentially read memory contents that should not be accessible.

The vulnerability affects applications that utilize the r:wsread() function to process incoming requests, particularly in environments using mod_lua or similar modules that interact with this API.

Detection Methods for CVE-2022-30556

Indicators of Compromise

Unusual memory access patterns in Apache HTTP Server process logs
Abnormal request patterns targeting endpoints that utilize r:wsread() functionality
Unexplained information exposure or data leakage from the web server
Elevated network traffic containing potentially sensitive server memory data

Detection Strategies

Monitor Apache HTTP Server access and error logs for suspicious request patterns
Implement network intrusion detection rules to identify exploitation attempts
Deploy web application firewalls (WAF) with rules to detect anomalous buffer-related requests
Utilize SentinelOne's behavioral AI to detect memory access anomalies associated with out-of-bounds read attempts

Monitoring Recommendations

Enable verbose logging for Apache HTTP Server to capture detailed request information
Configure alerting for unexpected memory allocation patterns in server processes
Monitor for applications making calls to r:wsread() and track returned length values
Implement continuous vulnerability scanning to identify unpatched Apache instances

How to Mitigate CVE-2022-30556

Immediate Actions Required

Upgrade Apache HTTP Server to version 2.4.54 or later immediately
Review server configurations and disable unnecessary modules that may use r:wsread()
Implement network segmentation to limit exposure of vulnerable servers
Apply vendor-specific patches for NetApp Clustered Data ONTAP and Fedora systems

Patch Information

Apache has addressed this vulnerability in versions released after 2.4.53. Administrators should consult the Apache HTTPD Vulnerability List for detailed patch information. Additional security advisories are available from:

Workarounds

If immediate patching is not possible, restrict access to Apache HTTP Server endpoints that utilize the vulnerable r:wsread() function
Disable mod_lua and other modules that may call r:wsread() if not required for operations
Implement strict firewall rules to limit access to the Apache HTTP Server from trusted networks only
Deploy a reverse proxy or WAF in front of vulnerable servers to filter malicious requests

bash

# Configuration example - Disable mod_lua if not required
# In Apache configuration file (httpd.conf or apache2.conf):
# Comment out or remove the following line:
# LoadModule lua_module modules/mod_lua.so

# Verify Apache version after upgrade:
httpd -v
# or
apache2 -v

# Expected output should show version 2.4.54 or later