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
# 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
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
