CVE-2019-18348: Python

Medium severity, CVSS 6.1. EPSS: 3.5% chance of exploitation in the next 30 days.

An issue was discovered in urllib2 in Python 2.x through 2.7.17 and urllib in Python 3.x through 3.8.0. CRLF injection is possible if the attacker controls a url parameter, as demonstrated by the first argument to urllib.request.urlopen with \r\n (specifically in the host component of a URL) followed by an HTTP header. This is similar to the CVE-2019-9740 query string issue and the CVE-2019-9947 path string issue. (This is not exploitable when glibc has CVE-2016-10739 fixed.). This is fixed in: v2.7.18, v2.7.18rc1; v3.5.10, v3.5.10rc1; v3.6.11, v3.6.11rc1, v3.6.12; v3.7.8, v3.7.8rc1, v3.7.9; v3.8.3, v3.8.3rc1, v3.8.4, v3.8.4rc1, v3.8.5, v3.8.6, v3.8.6rc1.

Affected products

• Python Python: from 2.0, up to and including 2.7.17; from 3.0, before 3.5.10 (fixed in 3.5.10); from 3.6.0, before 3.6.11 (fixed in 3.6.11); from 3.7.0, before 3.7.8 (fixed in 3.7.8); from 3.8.0, before 3.8.3 (fixed in 3.8.3)

Published 2019-10-23. Last modified 2026-10-07.