CVE-2021-33197

Name: CVE-2021-33197
Creator: NVD / NIST
Published: 2021-08-02T19:15:08.493+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 2.26%

Last modified Jun 17, 2026

CVE-2021-33197 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. In Go before 1.15.13 and 1.16.x before 1.16.5, some configurations of ReverseProxy (from net/http/httputil) result in a situation where an attacker is able to drop arbitrary headers.. EPSS estimates a 2.26% chance of exploitation in the next 30 days.

Description

In Go before 1.15.13 and 1.16.x before 1.16.5, some configurations of ReverseProxy (from net/http/httputil) result in a situation where an attacker is able to drop arbitrary headers.

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

2.26%

80.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-862

Affected Software

Vendor	Product	Versions
Golang	Go	< 1.15.13
Golang	Go	>= 1.16.0, < 1.16.5

References

https://groups.google.com/g/golang-announceThird Party Advisory
https://groups.google.com/g/golang-announce/c/RgCMkAEQjSIExploit, Patch, Third Party Advisory
https://security.gentoo.org/glsa/202208-02Third Party Advisory
https://groups.google.com/g/golang-announceThird Party Advisory
https://groups.google.com/g/golang-announce/c/RgCMkAEQjSIExploit, Patch, Third Party Advisory
https://security.gentoo.org/glsa/202208-02Third Party Advisory

Timeline

Published: Aug 2, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-33197?

In Go before 1.15.13 and 1.16.x before 1.16.5, some configurations of ReverseProxy (from net/http/httputil) result in a situation where an attacker is able to drop arbitrary headers.

How severe is CVE-2021-33197?

CVE-2021-33197 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 2.26% probability of exploitation in the next 30 days.

How do I fix CVE-2021-33197?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-33197?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST