CVE-2025-67726 - Tornado is Vulnerable to Quadratic DoS via Crafted Multipart Parameters

CVE ID : CVE-2025-67726 Published : Dec. 12, 2025, 7:15 a.m. | 32 minutes ago Description : Tornado is a Python web framework and asynchronous networking library. Versions 6.5.2 and below use an inefficient algorithm when parsing parameters for HTTP header values, potentially causing a DoS. The _parseparam function in httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data and repeatedly calls string.count() within a nested loop while processing quoted semicolons. If an attacker sends a request with a large number of maliciously crafted parameters in a Content-Disposition header, the server's CPU usage increases quadratically (O(n²)) during parsing. Due to Tornado's single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period. This issue is fixed in version 6.5.3. Severity: 7.5 | HIGH Visit the link for more details, such as CVSS details, affected products, timeline, and more...

Source: Telegram CVE Monitor