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CVE-2016-5421

32
FAUCET Score

CVE-2016-5421 is a high-severity use-after-free vulnerability in libcurl versions prior to 7.50.1, impacting various products including Canonical, Debian, FedoraProject, Haxx, and openSUSE. This flaw, with a CVSS score of 8.1, allows remote attackers to manipulate connection usage or achieve other unspecified impacts with high confidentiality, integrity, and availability consequences, despite requiring high attack complexity. There is no evidence of active exploitation, publicly available exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
42.1CPE matchmatch criteria
cpe:2.3:o:opensuse:leap:42.1:*:*:*:*:*:*:*
<= 7.50.0CPE matchmatch criteria
cpe:2.3:a:haxx:libcurl:*:*:*:*:*:*:*:*
12.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:*
14.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
16.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.1HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
8.04%
Probability of exploitation in next 30 days
EPSS Percentile
94.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0804 is in the 73rd percentile among its peer group of 8,920 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

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

Remediation

Patch Available

Vendor Patches (20)

jitsipatch availablevia llm_extracted
Fixed in: 7.50.0
View patch
oraclepatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6Fixed in: httpd24-curl-0:7.61.1-1.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6Fixed in: httpd24-nghttp2-0:1.7.1-7.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: httpd24-curl-0:7.61.1-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: httpd24-httpd-0:2.4.34-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: httpd24-nghttp2-0:1.7.1-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.4 EUSFixed in: httpd24-curl-0:7.61.1-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.4 EUSFixed in: httpd24-httpd-0:2.4.34-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.4 EUSFixed in: httpd24-nghttp2-0:1.7.1-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUSFixed in: httpd24-curl-0:7.61.1-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUSFixed in: httpd24-httpd-0:2.4.34-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUSFixed in: httpd24-nghttp2-0:1.7.1-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUSFixed in: httpd24-curl-0:7.61.1-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUSFixed in: httpd24-httpd-0:2.4.34-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUSFixed in: httpd24-nghttp2-0:1.7.1-7.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6Fixed in: httpd24-httpd-0:2.4.34-7.el6
View patch
sierra_wirelesspatch availablevia llm_extracted
Fixed in: 7.50.0
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Virtualization 3Fixed in: mingw-virt-viewer
redhatend of lifevia redhat_api
Product: .NET Core 2.1 on Red Hat Enterprise LinuxFixed in: rh-dotnet21-curl

Vendor Advisories (3)

redhatCVE-2016-5421Moderate

curl: Use of connection struct after free

Aug 3, 2016
sierra_wirelessllm-sierra_wireless-0901c86e85f1bd61HIGH

use of connection struct after free

Aug 3, 2016
jitsillm-jitsi-134368c1ad0a704cHIGH

use of connection struct after free

Aug 3, 2016

References

lists.opensuse.org / opensuse-updates/2016-09/msg00011.html
Third Party Advisory
lists.opensuse.org / opensuse-updates/2016-09/msg00094.html
Third Party Advisory
access.redhat.com / errata/RHSA-2018:3558
Third Party Advisory
curl.haxx.se / docs/adv_20160803C.html
MitigationVendor Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/GLPXQQKURBQFM4XM6645VRPTOE2AWG33
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/K3GQH4V3XAQ5Z53AMQRDEC3C3UHTW7QR
security.gentoo.org / glsa/201701-47
Third Party Advisory
source.android.com / security/bulletin/2016-12-01.html
Third Party Advisory
tenable.com / security/tns-2016-18
Third Party Advisory
debian.org / security/2016/dsa-3638
Third Party Advisory
oracle.com / technetwork/security-advisory/cpuoct2018-4428296.html
PatchThird Party Advisory
securityfocus.com / bid/92306
Third Party AdvisoryVDB Entry
securitytracker.com / id/1036536
Third Party AdvisoryVDB Entry
slackware.com / security/viewer.php
Third Party Advisory
ubuntu.com / usn/USN-3048-1
Third Party Advisory