CVE-2019-9947: Python

Medium severity, CVSS 6.1. EPSS: 5.3% chance of exploitation in the next 30 days.

An issue was discovered in urllib2 in Python 2.x through 2.7.16 and urllib in Python 3.x through 3.7.3. 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 path component of a URL that lacks a ? character) followed by an HTTP header or a Redis command. This is similar to the CVE-2019-9740 query string issue. This is fixed in: v2.7.17, v2.7.17rc1, v2.7.18, v2.7.18rc1; v3.5.10, v3.5.10rc1, v3.5.8, v3.5.8rc1, v3.5.8rc2, v3.5.9; v3.6.10, v3.6.10rc1, v3.6.11, v3.6.11rc1, v3.6.12, v3.6.9, v3.6.9rc1; v3.7.4, v3.7.4rc1, v3.7.4rc2, v3.7.5, v3.7.5rc1, v3.7.6, v3.7.6rc1, v3.7.7, v3.7.7rc1, v3.7.8, v3.7.8rc1, v3.7.9.

Affected products

• Python Python: from 2.7.0, before 2.7.17 (fixed in 2.7.17); from 3.5.0, before 3.5.8 (fixed in 3.5.8); from 3.6.0, before 3.6.9 (fixed in 3.6.9); from 3.7.0, before 3.7.4 (fixed in 3.7.4)

Published 2019-03-23. Last modified 2026-10-07.