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Fencer Vulns
high 8.1

CVE-2016-5421 json

Use-after-free vulnerability in libcurl before 7.50.1 allows attackers to control which connection is used or possibly have unspecified oth…

published 2016-08-10 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-6366

cvss
8.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
8.0%
EPSS 8.0% chance of exploitation in 30 days, percentile 94%
public exploits
0
none known

Summary

Use-after-free vulnerability in libcurl before 7.50.1 allows attackers to control which connection is used or possibly have unspecified other impact via unknown vectors.

Patch / fix

  • curl Debian 14, Debian 13, Debian 12 7.50.1-1

debian advisories DEBIAN-CVE-2016-5421

  • curl Ubuntu 14.04 LTS 7.35.0-1ubuntu2.8
  • curl Ubuntu 16.04 LTS 7.47.0-1ubuntu2.1

ubuntu advisories UBUNTU-CVE-2016-5421

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • httpd24-curl RHEL 3 SOFTWARE_COLLECTIONS 7.61.1-1.el6
  • httpd24-curl RHEL 3 SOFTWARE_COLLECTIONS 7.61.1-1.el7
  • httpd24-httpd RHEL 3 SOFTWARE_COLLECTIONS 2.4.34-7.el6
  • httpd24-httpd RHEL 3 SOFTWARE_COLLECTIONS 2.4.34-7.el7
  • httpd24-mod_md RHEL 3 SOFTWARE_COLLECTIONS 2.4.34-7.el7
  • httpd24-libcurl RHEL 3 SOFTWARE_COLLECTIONS 7.61.1-1.el6
  • httpd24-libcurl RHEL 3 SOFTWARE_COLLECTIONS 7.61.1-1.el7
  • httpd24-mod_ssl RHEL 3 SOFTWARE_COLLECTIONS 1:2.4.34-7.el6

red hat advisories RHSA-2018:3558

  • curl SLES for SAP 12 SP1, SLES 12 SP1, SLED 12 SP1 +1 more 7.37.0-28.1

suse advisories SUSE-SU-2016:2330-1

  • curl Alpine 3.24, Alpine 3.23, Alpine 3.22 +14 more 7.50.1-r0
  • curl Alpine 3.11, Alpine 3.8, Alpine 3.7 +1 more 7.50.1
  • curl Alpine 3.3, Alpine 3.2 7.49.1-r1

alpine advisories ALPINE-CVE-2016-5421

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-5421 updated cvss 8.1

curl: Use of connection struct after free

  • Red Hat .NET Core 1.0 on Red Hat Enterprise Linux rh-dotnetcore10-curl Red Hat .NET Core 1.1 on Red Hat Enterprise Linux rh-dotnetcore11-curl Red Hat .NET Core 2.0 on Red Hat Enterprise Linux rh-dotnet20-curl
    affected: no fix planned “Out of support scope”
  • Red Hat .NET Core 2.1 on Red Hat Enterprise Linux rh-dotnet21-curl, rh-dotnet21-libcurl Red Hat Enterprise Virtualization 3 mingw-virt-viewer, mingw32-virt-viewer, mingw64-virt-viewer
    affected: no fix planned “Will not fix”
  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 6) httpd24-curl 7.61.1-1.el6, httpd24-httpd 2.4.34-7.el6, httpd24-nghttp2 1.7.1-7.el6, httpd24-libcurl 7.61.1-1.el6, httpd24-mod_ssl 2.4.34-7.el6, httpd24-mod_ldap 2.4.34-7.el6, +5 more Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) httpd24-curl 7.61.1-1.el7, httpd24-httpd 2.4.34-7.el7, httpd24-mod_md 2.4.34-7.el7, httpd24-nghttp2 1.7.1-7.el7, httpd24-libcurl 7.61.1-1.el7, httpd24-mod_ssl 2.4.34-7.el7, +6 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.4) httpd24-curl 7.61.1-1.el7, httpd24-httpd 2.4.34-7.el7, httpd24-mod_md 2.4.34-7.el7, httpd24-nghttp2 1.7.1-7.el7, httpd24-libcurl 7.61.1-1.el7, httpd24-mod_ssl 2.4.34-7.el7, +6 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.5) httpd24-curl 7.61.1-1.el7, httpd24-httpd 2.4.34-7.el7, httpd24-mod_md 2.4.34-7.el7, httpd24-nghttp2 1.7.1-7.el7, httpd24-libcurl 7.61.1-1.el7, httpd24-mod_ssl 2.4.34-7.el7, +6 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.6) httpd24-curl 7.61.1-1.el7, httpd24-httpd 2.4.34-7.el7, httpd24-mod_md 2.4.34-7.el7, httpd24-nghttp2 1.7.1-7.el7, httpd24-libcurl 7.61.1-1.el7, httpd24-mod_ssl 2.4.34-7.el7, +6 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 6) httpd24-curl 7.61.1-1.el6, httpd24-httpd 2.4.34-7.el6, httpd24-nghttp2 1.7.1-7.el6, httpd24-libcurl 7.61.1-1.el6, httpd24-mod_ssl 2.4.34-7.el6, httpd24-mod_ldap 2.4.34-7.el6, +5 more
    +1 more products
    Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) httpd24-curl 7.61.1-1.el7, httpd24-httpd 2.4.34-7.el7, httpd24-mod_md 2.4.34-7.el7, httpd24-nghttp2 1.7.1-7.el7, httpd24-libcurl 7.61.1-1.el7, httpd24-mod_ssl 2.4.34-7.el7, +6 more
    fixed: vendor fix RHSA-2018:3558
  • Red Hat Enterprise Linux 5 curl Red Hat Enterprise Linux 6 curl, libcurl Red Hat Enterprise Linux 7 curl, libcurl Red Hat JBoss Enterprise Web Server 3 curl
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

8.04% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.