CVE-2019-9947: CRLF Injection

Published Mar 23, 2019
·
Updated

An issue was discovered in urllib2 in Python 2.x through 2.7.16 and urllib in Python 3.x through 3.7.2. 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) followed by an HTTP header or a Redis command. This is similar to CVE-2019-9740 query string issue.

Reference: https://bugs.python.org/issue35906

Other sources

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 Software

19 affected componentsFixes available
redhat/python<0:2.7.5-86.el7
0:2.7.5-86.el7
redhat/python<0:2.7.5-63.el7_4
0:2.7.5-63.el7_4
redhat/python<0:2.7.5-74.el7_5
0:2.7.5-74.el7_5
redhat/python<0:2.7.5-83.el7_6
0:2.7.5-83.el7_6
redhat/python3<0:3.6.8-15.1.el8
0:3.6.8-15.1.el8
redhat/python27-python<0:2.7.16-4.el6
0:2.7.16-4.el6
redhat/python27-python-jinja2<0:2.6-12.el6
0:2.6-12.el6
redhat/rh-python36-python<0:3.6.9-2.el6
0:3.6.9-2.el6
redhat/python27-python<0:2.7.16-4.el7
0:2.7.16-4.el7
redhat/python27-python-jinja2<0:2.6-15.el7
0:2.6-15.el7
redhat/rh-python36-python<0:3.6.9-2.el7
0:3.6.9-2.el7
debian/python2.7
2.7.18-8+deb11u1
Python Python>=2.7.0<2.7.17
Python Python>=3.5.0<3.5.8
Python Python>=3.6.0<3.6.9
Python Python>=3.7.0<3.7.4
F5 BIG-IP=17.5.0, >=17.1.0<=17.1.2
17.5.117.1.3
F5 BIG-IP>=16.1.0<=16.1.6
F5 BIG-IP>=15.1.0<=15.1.10

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade redhat/python to a version that resolves this vulnerability.

    Fixed in 0:2.7.5-86.el7
  2. Upgrade

    Upgrade redhat/python to a version that resolves this vulnerability.

    Fixed in 0:2.7.5-63.el7_4
  3. Upgrade

    Upgrade redhat/python to a version that resolves this vulnerability.

    Fixed in 0:2.7.5-74.el7_5
  4. Upgrade

    Upgrade redhat/python to a version that resolves this vulnerability.

    Fixed in 0:2.7.5-83.el7_6
  5. Upgrade

    Upgrade redhat/python3 to a version that resolves this vulnerability.

    Fixed in 0:3.6.8-15.1.el8
  6. Upgrade

    Upgrade redhat/python27-python to a version that resolves this vulnerability.

    Fixed in 0:2.7.16-4.el6
  7. Upgrade

    Upgrade redhat/python27-python-jinja2 to a version that resolves this vulnerability.

    Fixed in 0:2.6-12.el6
  8. Upgrade

    Upgrade redhat/rh-python36-python to a version that resolves this vulnerability.

    Fixed in 0:3.6.9-2.el6
  9. Upgrade

    Upgrade redhat/python27-python to a version that resolves this vulnerability.

    Fixed in 0:2.7.16-4.el7
  10. Upgrade

    Upgrade redhat/python27-python-jinja2 to a version that resolves this vulnerability.

    Fixed in 0:2.6-15.el7
  11. Upgrade

    Upgrade redhat/rh-python36-python to a version that resolves this vulnerability.

    Fixed in 0:3.6.9-2.el7
  12. Upgrade

    Upgrade debian/python2.7 to a version that resolves this vulnerability.

    Fixed in 2.7.18-8+deb11u1
  13. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 17.5.117.1.3
  14. Upgrade

    Upgrade Python 2.7 to a version that resolves this vulnerability.

    Fixed in v2.7.17
  15. Upgrade

    Upgrade Python 2.7 to a version that resolves this vulnerability.

    Fixed in v2.7.18
  16. Upgrade

    Upgrade Python 3.5 to a version that resolves this vulnerability.

    Fixed in v3.5.10
  17. Upgrade

    Upgrade Python 3.6 to a version that resolves this vulnerability.

    Fixed in v3.6.10
  18. Upgrade

    Upgrade Python 3.6 to a version that resolves this vulnerability.

    Fixed in v3.6.11
  19. Upgrade

    Upgrade Python 3.6 to a version that resolves this vulnerability.

    Fixed in v3.6.12
  20. Upgrade

    Upgrade Python 3.7 to a version that resolves this vulnerability.

    Fixed in v3.7.4
  21. Upgrade

    Upgrade Python 3.7 to a version that resolves this vulnerability.

    Fixed in v3.7.5
  22. Upgrade

    Upgrade Python 3.7 to a version that resolves this vulnerability.

    Fixed in v3.7.6
  23. Upgrade

    Upgrade Python 3.7 to a version that resolves this vulnerability.

    Fixed in v3.7.7
  24. Upgrade

    Upgrade Python 3.7 to a version that resolves this vulnerability.

    Fixed in v3.7.8
  25. Upgrade

    Upgrade Python 3.7 to a version that resolves this vulnerability.

    Fixed in v3.7.9

Event History

Mar 23, 2019
CVE Published
12:00 AM
CVE Published
via MITRE·05:06 PM
Data Sourced
via MITRE·05:06 PM
Description
Apr 3, 2019
Data Sourced
via Red Hat·11:41 AM
DescriptionSeverityAffected Software
May 27, 2025
Advisory Published
via F5·04:24 PM
Data Sourced
via F5·04:24 PM
DescriptionSeverityWeaknessAffected Software
Feb 20, 2026
Data Sourced
via Ubuntu·07:03 PM
RemedyDescriptionSeverityAffected Software
Data Sourced
via Launchpad·07:03 PM
Description

Parent advisories

This vulnerability appears in the following advisories.

Frequently Asked Questions

1

What is CVE-2019-9947?

CVE-2019-9947 is a vulnerability in urllib2 in Python 2.x and urllib in Python 3.x that allows for CRLF injection if the attacker controls a URL parameter.

2

What is the severity of CVE-2019-9947?

CVE-2019-9947 has a severity score of 6.5 (medium).

3

Which versions of Python are affected by CVE-2019-9947?

Python 2.x versions up to 2.7.16 and Python 3.x versions up to 3.7.3 are affected by CVE-2019-9947.

4

How can CRLF injection be prevented in urllib2 and urllib?

To prevent CRLF injection in urllib2 and urllib, it is recommended to carefully validate and sanitize user-supplied input before using it in a URL.

5

Where can I find more information about CVE-2019-9947?

You can find more information about CVE-2019-9947 on the Red Hat Security Advisory website and the Python bug tracker.

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