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CVE-2016-5699

24
FAUCET Score

CVE-2016-5699 describes a CRLF injection vulnerability in the HTTPConnection.putheader function within Python's urllib2 and urllib libraries, affecting versions prior to 2.7.10 and 3.4.4 respectively. This flaw allows remote attackers to inject arbitrary HTTP headers by embedding CRLF sequences in a URL. Rated as Medium severity (CVSS 6.1), it requires user interaction and could lead to partial confidentiality and integrity impacts. There is no evidence of active exploitation, readily available exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.7.9CPE matchmatch criteria
cpe:2.3:a:python:python:*:*:*:*:*:*:*:*
3.0CPE matchmatch criteria
cpe:2.3:a:python:python:3.0:*:*:*:*:*:*:*
3.0.1CPE matchmatch criteria
cpe:2.3:a:python:python:3.0.1:*:*:*:*:*:*:*
3.1.0CPE matchmatch criteria
cpe:2.3:a:python:python:3.1.0:*:*:*:*:*:*:*
3.1.1CPE matchmatch criteria
cpe:2.3:a:python:python:3.1.1:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

6.1MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.0

Exploit Intelligence

EPSS Score
10.24%
Probability of exploitation in next 30 days
EPSS Percentile
95.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.1024 is in the 98th percentile among its peer group of 26,219 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

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