nginx range filter integer overflow
Description
CVE-2017-7529 is an integer overflow vulnerability in the nginx range filter module that affects versions 0.5.6 through 1.13.2. When processing specially crafted HTTP Range requests, an integer overflow occurs during range boundary calculations, leading to incorrect memory access and potential information disclosure. This vulnerability was fixed in nginx versions 1.12.1 and 1.13.3.
In standard configurations, attackers can exploit this flaw to retrieve cache file headers containing sensitive data such as backend server IP addresses, internal paths, or configuration details. When third-party modules are present, the vulnerability may potentially lead to worker process memory disclosure or denial of service, though no such modules have been publicly identified.
Remediation
Immediately upgrade nginx to a patched version to remediate this vulnerability:
1. For nginx 1.13.x users: Upgrade to version 1.13.3 or later
2. For nginx 1.12.x users: Upgrade to version 1.12.1 or later
3. For older stable branches: Upgrade to the latest stable release (1.12.1 or higher)
Upgrade Steps:
- Backup your current nginx configuration files
- Download the appropriate patched version from the official nginx repository
- Test the new version in a staging environment before production deployment
- Apply the upgrade during a scheduled maintenance window
- Verify the installation by checking the version:
nginx -v- Review nginx error logs after upgrade to ensure proper operation
Temporary Mitigation: If immediate patching is not possible, consider implementing rate limiting and request filtering at the perimeter to reduce exposure, though upgrading remains the only complete solution.