CVE-2016-5420

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Summary

CVECVE-2016-5420
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2016-08-10 14:59:05 UTC
Updated2026-05-06 22:30:45 UTC
Descriptioncurl 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.

Risk And Classification

Primary CVSS: v3.0 7.5 HIGH from [email protected]

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

EPSS: 0.145960000 probability, percentile 0.962700000 (date 2026-07-21)

Problem Types: CWE-285 | n/a

VersionSourceTypeScoreSeverityVector
3.0[email protected]Primary7.5HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
2.0[email protected]Primary5AV:N/AC:L/Au:N/C:N/I:P/A:N

CVSS v3.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

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

CVSS v2.0 Breakdown

Access Vector
Network
Access Complexity
Low
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
None

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Debian Debian Linux 8.0 All All All
Application Haxx Libcurl All All All All
Operating System Opensuse Leap 42.1 All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Na N/a affected n/a Not specified

References

ReferenceSourceLinkTags
CPU Oct 2018 af854a3a-2127-422b-91ae-364da2661108 www.oracle.com
[SECURITY] Fedora 24 Update: curl-7.47.1-6.fc24 - package-announce - Fedora Mailing-Lists af854a3a-2127-422b-91ae-364da2661108 lists.fedoraproject.org
[R7] LCE 4.8.1 Fixes Multiple Vulnerabilities - Security Advisory | Tenable™ af854a3a-2127-422b-91ae-364da2661108 www.tenable.com
openSUSE-SU-2016:2379-1: moderate: Security update for curl af854a3a-2127-422b-91ae-364da2661108 lists.opensuse.org Third Party Advisory
curl - Re-using connections with wrong client cert af854a3a-2127-422b-91ae-364da2661108 curl.haxx.se Mitigation, Patch, Vendor Advisory
Red Hat Customer Portal af854a3a-2127-422b-91ae-364da2661108 rhn.redhat.com
Red Hat Customer Portal af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
USN-3048-1: curl vulnerabilities | Ubuntu af854a3a-2127-422b-91ae-364da2661108 www.ubuntu.com
cURL/libcurl Certificate Reuse Bug Lets Remote Users Bypass Security Restrictions on the Target System - SecurityTracker af854a3a-2127-422b-91ae-364da2661108 www.securitytracker.com
Android Security Bulletin—December 2016 | Android Open Source Project af854a3a-2127-422b-91ae-364da2661108 source.android.com
cURL/libcurl TLS Connection Reuse Bug Lets Remote Users Bypass Security Restrictions on the Target System - SecurityTracker af854a3a-2127-422b-91ae-364da2661108 www.securitytracker.com
Red Hat Customer Portal af854a3a-2127-422b-91ae-364da2661108 rhn.redhat.com
openSUSE-SU-2016:2227-1: moderate: Security update for curl af854a3a-2127-422b-91ae-364da2661108 lists.opensuse.org
[SECURITY] Fedora 23 Update: curl-7.43.0-8.fc23 - package-announce - Fedora Mailing-Lists af854a3a-2127-422b-91ae-364da2661108 lists.fedoraproject.org
cURL/libcURL CVE-2016-5420 Certificate Validation Security Bypass Vulnerability af854a3a-2127-422b-91ae-364da2661108 www.securityfocus.com
cURL: Multiple vulnerabilities (GLSA 201701-47) — Gentoo security af854a3a-2127-422b-91ae-364da2661108 security.gentoo.org
Debian -- Security Information -- DSA-3638-1 curl af854a3a-2127-422b-91ae-364da2661108 www.debian.org Third Party Advisory
The Slackware Linux Project: Slackware Security Advisories af854a3a-2127-422b-91ae-364da2661108 www.slackware.com
[SECURITY] Fedora 24 Update: curl-7.47.1-6.fc24 - package-announce - Fedora Mailing-Lists MITRE lists.fedoraproject.org
[SECURITY] Fedora 23 Update: curl-7.43.0-8.fc23 - package-announce - Fedora Mailing-Lists MITRE lists.fedoraproject.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 500111 Alpine Linux Security Update for curl
  • 503766 Alpine Linux Security Update for curl
  • 710385 Gentoo Linux cURL Multiple Vulnerabilities (GLSA 201701-47)

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