{"id":"ALPINE-CVE-2025-67726","details":"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.","modified":"2026-11-03T06:33:01.050793635Z","published":"2025-12-12T07:15:44.920Z","upstream":["CVE-2025-67726"],"references":[{"type":"ADVISORY","url":"https://security.alpinelinux.org/vuln/CVE-2025-67726"}],"affected":[{"package":{"name":"py3-tornado","ecosystem":"Alpine:v3.23","purl":"pkg:apk/alpine/py3-tornado?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.5.4-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2025-67726.json"}},{"package":{"name":"py3-tornado","ecosystem":"Alpine:v3.24","purl":"pkg:apk/alpine/py3-tornado?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.5.4-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2025-67726.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}