CVE-2019-9740 - Improper Neutralization of CRLF Sequences ('CRLF Injection')

Severity

43%

Complexity

86%

Confidentiality

48%

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 query string after a ? character) followed by an HTTP header or a Redis command.

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 query string after a ? character) followed by an HTTP header or a Redis command.

CVSS 3.0 Base Score 6.1. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N).

CVSS 2.0 Base Score 4.3. CVSS Attack Vector: network. CVSS Attack Complexity: medium. CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:P/A:N).

Demo Examples

Improper Neutralization of CRLF Sequences ('CRLF Injection')

CWE-93

If user input data that eventually makes it to a log message isn't checked for CRLF characters, it may be possible for an attacker to forge entries in a log file.


               
logger.info("User's street address: " + request.getParameter("streetAddress"));

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