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Vulnerability record · CVE-2016-5699 · published 2 September 2016

CVE-2016-5699: Python vulnerability

Python · Python

CRLF injection vulnerability in the HTTPConnection.putheader function in urllib2 and urllib in CPython (aka Python) before 2.7.10 and 3.x before 3.4.4 allows remote attackers to inject arbitrary HTTP headers via CRLF sequences in a URL.

6.1 CVSS 3.0 Medium EPSS 9.9% · top 4.6% CWE-113 · CWE-113
6.1CVSS 3.0 base score, v2 4.3
9.9%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
38References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

CRLF injection vulnerability in the HTTPConnection.putheader function in urllib2 and urllib in CPython (aka Python) before 2.7.10 and 3.x before 3.4.4 allows remote attackers to inject arbitrary HTTP headers via CRLF sequences in a URL.

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://blog.blindspotsecurity.com/2016/06/advisory-http-header-injection-in.html ExploitThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
http://rhn.redhat.com/errata/RHSA-2016-1626.html
http://rhn.redhat.com/errata/RHSA-2016-1627.html
http://rhn.redhat.com/errata/RHSA-2016-1628.html
http://rhn.redhat.com/errata/RHSA-2016-1629.html
http://rhn.redhat.com/errata/RHSA-2016-1630.html
http://www.openwall.com/lists/oss-security/2016/06/14/7 Mailing List
http://www.openwall.com/lists/oss-security/2016/06/15/12 Mailing List
http://www.openwall.com/lists/oss-security/2016/06/16/2 Mailing List
http://www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html
http://www.securityfocus.com/bid/91226
http://www.splunk.com/view/SP-CAAAPSV
http://www.splunk.com/view/SP-CAAAPUE
https://docs.python.org/3.4/whatsnew/changelog.html#python-3-4-4 Release Notes
https://hg.python.org/cpython/raw-file/v2.7.10/Misc/NEWS Release Notes
https://hg.python.org/cpython/rev/1c45047c5102 Patch
https://hg.python.org/cpython/rev/bf3e1c9b80e9 Patch
https://lists.debian.org/debian-lts-announce/2019/02/msg00011.html
http://blog.blindspotsecurity.com/2016/06/advisory-http-header-injection-in.html ExploitThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
http://rhn.redhat.com/errata/RHSA-2016-1626.html
http://rhn.redhat.com/errata/RHSA-2016-1627.html
http://rhn.redhat.com/errata/RHSA-2016-1628.html
http://rhn.redhat.com/errata/RHSA-2016-1629.html
http://rhn.redhat.com/errata/RHSA-2016-1630.html
http://www.openwall.com/lists/oss-security/2016/06/14/7 Mailing List
http://www.openwall.com/lists/oss-security/2016/06/15/12 Mailing List
http://www.openwall.com/lists/oss-security/2016/06/16/2 Mailing List
http://www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html
http://www.securityfocus.com/bid/91226
http://www.splunk.com/view/SP-CAAAPSV
http://www.splunk.com/view/SP-CAAAPUE
https://docs.python.org/3.4/whatsnew/changelog.html#python-3-4-4 Release Notes
https://hg.python.org/cpython/raw-file/v2.7.10/Misc/NEWS Release Notes
https://hg.python.org/cpython/rev/1c45047c5102 Patch
https://hg.python.org/cpython/rev/bf3e1c9b80e9 Patch
https://lists.debian.org/debian-lts-announce/2019/02/msg00011.html

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Source: NIST National Vulnerability Database (record CVE-2016-5699), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.