CVE-2013-4366

Hostname verification in Apache HttpClient 4.3 was disabled by default

9.8 CriticalFix available

http/impl/client/HttpClientBuilder.java in Apache HttpClient 4.3.x before 4.3.1 does not ensure that X509HostnameVerifier is not null, which allows attackers to have unspecified impact via vectors involving hostname verification.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

3.31%Up 2.4 points since Feb 4, 2022

What each source reports

NVD Score used 9.8

Record: CVE-2013-4366
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0: 7.5 HighAV:N/AC:L/Au:N/C:P/I:P/A:P
Weakness: CWE-20
Updated: 2026-11-02

CVE List No score

Record: CVE-2013-4366
Updated: 2026-11-02

EUVDEUVD-2022-4812 No score

Record: EUVD-2022-4812
Updated: 2026-11-03

GitHub AdvisoriesGHSA-pqwh-44jj-p5rm 9.8

Hostname verification in Apache HttpClient 4.3 was disabled by default

Record: GHSA-pqwh-44jj-p5rm
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-20
Updated: 2026-11-02

OSV 9.8

Record: CVE-2013-4366
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2013-4366 9.8

Record: DEBIAN-CVE-2013-4366
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVGHSA-pqwh-44jj-p5rm 9.8

Hostname verification in Apache HttpClient 4.3 was disabled by default

Record: GHSA-pqwh-44jj-p5rm
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-20
Updated: 2026-11-02

OSVUBUNTU-CVE-2013-4366 9.8

Record: UBUNTU-CVE-2013-4366
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 3.0: 9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

Affected products

apache httpclient

Affected packages

Affected packages
Package	Affected	Fixed
`org.apache.httpcomponents:httpclient` Maven	4.3 up to 4.3.1	4.3.1
`httpcomponents-client` Debian:12	before 4.3.2-1	4.3.2-1
`httpcomponents-client` Debian:13	before 4.3.2-1	4.3.2-1
`httpcomponents-client` Debian:14	before 4.3.2-1	4.3.2-1

History

History
Recorded	Changed	Sources
Nov 3, 2026	affected
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2013-4366 is a critical vulnerability (CVSS 9.8) in Apache Httpclient, published October 30, 2017. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 3.31%, the 88th percentile. Fixed in org.apache.httpcomponents:httpclient 4.3.1.