Vulnerability Report

CVE-2016-5420

Title: Haxx Libcurl Auth Bypass

Auth Bypass

Proof Of Concept

No public PoC currently indexed for CVE-2016-5420.

CWE Category CWE-285

Published Date Aug 10, 2016

Modified Date May 06, 2026

Exploit Status Not Found

Score 7.5 CVSS v3.0

Exploit Probability (EPSS)

14.60%

Vulnerability Summary

CVE-2016-5420: curl and libcurl before 7.50.1 do not check the client certificate when choosing the TLS connection to reuse, which might allow remote attackers to hijack the authentication of the connection by leveraging a previously created connection with a different client certificate.

Impacted Vendors

haxx 1

libcurl 1

Reference Links

http://lists.opensuse.org/opensuse-updates/2016-09/msg00011.html http://lists.opensuse.org/opensuse-updates/2016-09/msg00094.html http://rhn.redhat.com/errata/RHSA-2016-2575.html http://rhn.redhat.com/errata/RHSA-2016-2957.html http://www.debian.org/security/2016/dsa-3638 http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html http://www.securityfocus.com/bid/92309 http://www.securitytracker.com/id/1036537 http://www.securitytracker.com/id/1036739 http://www.slackware.com/security/viewer.php?l=slackware-security&y=2016&m=slackware-security.563059 http://www.ubuntu.com/usn/USN-3048-1 https://access.redhat.com/errata/RHSA-2018:3558 https://curl.haxx.se/docs/adv_20160803B.html https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GLPXQQKURBQFM4XM6645VRPTOE2AWG33/ https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/K3GQH4V3XAQ5Z53AMQRDEC3C3UHTW7QR/ https://security.gentoo.org/glsa/201701-47 https://source.android.com/security/bulletin/2016-12-01.html https://www.tenable.com/security/tns-2016-18 http://lists.opensuse.org/opensuse-updates/2016-09/msg00011.html http://lists.opensuse.org/opensuse-updates/2016-09/msg00094.html http://rhn.redhat.com/errata/RHSA-2016-2575.html http://rhn.redhat.com/errata/RHSA-2016-2957.html http://www.debian.org/security/2016/dsa-3638 http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html http://www.securityfocus.com/bid/92309 http://www.securitytracker.com/id/1036537 http://www.securitytracker.com/id/1036739 http://www.slackware.com/security/viewer.php?l=slackware-security&y=2016&m=slackware-security.563059 http://www.ubuntu.com/usn/USN-3048-1 https://access.redhat.com/errata/RHSA-2018:3558 https://curl.haxx.se/docs/adv_20160803B.html https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GLPXQQKURBQFM4XM6645VRPTOE2AWG33/ https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/K3GQH4V3XAQ5Z53AMQRDEC3C3UHTW7QR/ https://security.gentoo.org/glsa/201701-47 https://source.android.com/security/bulletin/2016-12-01.html https://www.tenable.com/security/tns-2016-18

CVSS v3.0

Source Entity [email protected]

Severity HIGH

7.5

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

RAW VECTOR CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS v2.0

Source Entity [email protected]

Severity MEDIUM

5.0

Access Vector

N/A

Authentication

N/A

RAW VECTOR AV:N/AC:L/Au:N/C:N/I:P/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2016-5420 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

May 06, 2026 MODIFIED

Vulnerability data updated via NVD.

April 12, 2025 MODIFIED

Vulnerability data or affected products updated.

August 10, 2016 PUBLISHED

Vulnerability first announced in NVD.

Attack Vector Matrix

Access Vector NETWORK

Complexity LOW

Privileges N/A

Interaction NONE

CVSS Vector String


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

Affected Stack

No specific products linked.