CVE-2018-1000164

Gunicorn contains Improper Neutralization of CRLF sequences in HTTP headers

7.5 HighFix available

gunicorn version 19.4.5 contains a CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers vulnerability in "process_headers" function in "gunicorn/http/wsgi.py" that can result in an attacker causing the server to return arbitrary HTTP headers. This vulnerability appears to have been fixed in 19.5.0.

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: None
Integrity: High
Availability: None

Exploit likelihood

2.37%Up 1.1 points since Apr 14, 2021

What each source reports

NVD Score used 7.5

Record: CVE-2018-1000164
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS 2.0: 5.0 MediumAV:N/AC:L/Au:N/C:N/I:P/A:N
Weakness: CWE-93
Updated: 2026-11-02

CVE List No score

Record: CVE-2018-1000164
Updated: 2026-11-02

EUVDEUVD-2018-0076 No score

Record: EUVD-2018-0076
Updated: 2026-11-03

GitHub AdvisoriesGHSA-32pc-xphx-q4f6 8.7

Gunicorn contains Improper Neutralization of CRLF sequences in HTTP headers

Record: GHSA-32pc-xphx-q4f6
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness: CWE-93
Updated: 2026-11-02

OSV 7.5

Record: CVE-2018-1000164
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated: 2026-11-02

OSVDEBIAN-CVE-2018-1000164 7.5

Record: DEBIAN-CVE-2018-1000164
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated: 2026-11-02

Show 4 moreShow less

OSVGHSA-32pc-xphx-q4f6 8.7

Gunicorn contains Improper Neutralization of CRLF sequences in HTTP headers

Record: GHSA-32pc-xphx-q4f6
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness: CWE-93
Updated: 2026-11-02

OSVUBUNTU-CVE-2018-1000164 7.5

Record: UBUNTU-CVE-2018-1000164
CVSS 3.0: 7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated: 2026-11-02

OSVPYSEC-2018-55 No score

Record: PYSEC-2018-55
Updated: 2026-11-02

OSVUSN-4022-1 No score

Gunicorn vulnerability

It was discovered that gunicorn improperly handled certain input. An attacker could potentially use this issue execute a cross-site scripting (XSS) attack.

Record: USN-4022-1
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`gunicorn` PyPI	before 19.5.0	19.5.0
`gunicorn` Debian:12	before 19.5.0-1	19.5.0-1
`gunicorn` Debian:13	before 19.5.0-1	19.5.0-1
`gunicorn` Debian:14	before 19.5.0-1	19.5.0-1
`gunicorn` Debian:7	before 0.14.5-3+deb7u2, plus listed versions 0.14.5-3+deb7u1	0.14.5-3+deb7u2
`gunicorn` Debian:8	before 19.0-1+deb8u1, plus listed versions 19.0-1	19.0-1+deb8u1
`gunicorn` PyPI	before 19.5.0, plus listed versions 0.10.10.00.10.10.11.00.11.1 Show 45 moreShow less 0.11.20.12.00.12.10.12.20.13.00.13.10.13.20.13.30.13.40.14.00.14.10.14.20.14.30.14.40.14.50.14.60.15.00.16.00.16.10.17.00.17.10.17.20.17.30.17.40.20.2.10.30.3.10.3.20.40.4.10.4.20.50.5.10.60.6.10.6.20.6.30.6.40.6.50.6.60.7.00.7.10.7.20.8.0	19.5.0
`gunicorn` Ubuntu:Pro:14.04:LTS	before 17.5-2ubuntu0.1~esm1, plus listed versions 17.5-217.5-2build1	17.5-2ubuntu0.1~esm1
`gunicorn` Ubuntu:16.04:LTS	before 19.4.5-1ubuntu1.1, plus listed versions 19.0-8ubuntu119.4.1-1ubuntu119.4.5-1ubuntu1	19.4.5-1ubuntu1.1

History

History
Recorded	Changed	Sources
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-2018-1000164 is a high vulnerability (CVSS 7.5) in Gunicorn, published April 18, 2018. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.37%, the 83rd percentile. Fixed in gunicorn 19.5.0.

References

Show 8 moreShow less

This page doesn't list everything

Left out here: 17 versions. The JSON record has them.