CVE-2017-7529

What it actually does

Integer overflow in the nginx range filter module causes the server to return memory contents beyond the intended response boundaries when processing specially crafted Range headers.

Why it matters to the business

Attackers may obtain sensitive server memory contents including configuration data or user information, increasing risk of data exposure and downstream compromise; high EPSS score indicates active exploit interest despite lack of KEV listing.

How an attack unfolds

An attacker sends an HTTP request containing a malicious Range header crafted to trigger the integer overflow in the range filter, causing nginx to leak adjacent memory in the HTTP response body.

How to fix it

Upgrade nginx to a version after 1.13.2; for Bitnami MediaWiki installations, upgrade to version 1.35.2 which includes the patched nginx component.

How to confirm the fix worked

Confirm nginx version exceeds 1.13.2 via server banner or configuration checks; replay known malicious Range header test cases and verify responses contain only expected content without extraneous memory data.

Typical attack path

1. Identify nginx server running vulnerable version between 0.5.6 and 1.13.2
2. Craft HTTP GET request with specially malformed Range header values
3. Send request and inspect response for leaked memory contents
4. Parse leaked data for sensitive information to enable further attacks

How to detect it

Search web server access logs for HTTP requests containing Range headers with unusually large, negative, or overlapping byte ranges; examine responses for content-length values inconsistent with requested ranges.

• Range: bytes=0-,1-
• HTTP responses with content containing non-HTML binary fragments after normal page data
• nginx access logs showing Range headers with values exceeding 2^31

What your security team should do

• Prioritize upgrade of all affected nginx instances within 30 days given stable high EPSS
• Implement web application firewall rules to block suspicious Range headers
• Review and harden response headers to minimize information leakage