CVE-2021-23409

Name: CVE-2021-23409
Creator: NVD / NIST
Published: 2021-07-21T07:15:07.547+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.65%

Last modified Jun 17, 2026

CVE-2021-23409 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. The package github.com/pires/go-proxyproto before 0.6.0 are vulnerable to Denial of Service (DoS) via creating connections without the proxy protocol header.. EPSS estimates a 1.65% chance of exploitation in the next 30 days.

Description

The package github.com/pires/go-proxyproto before 0.6.0 are vulnerable to Denial of Service (DoS) via creating connections without the proxy protocol header.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

1.65%

73.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Go-Proxyproto Project	Go-Proxyproto	< 0.6.0

References

https://github.com/pires/go-proxyproto/issues/65Issue Tracking, Third Party Advisory
https://github.com/pires/go-proxyproto/pull/74Patch, Third Party Advisory
https://github.com/pires/go-proxyproto/pull/74/commits/cdc63867da24fc609b727231f682670d0d1cd346Patch, Third Party Advisory
https://github.com/pires/go-proxyproto/releases/tag/v0.6.0Release Notes, Third Party Advisory
https://snyk.io/vuln/SNYK-GOLANG-GITHUBCOMPIRESGOPROXYPROTO-1316439Patch, Third Party Advisory
https://github.com/pires/go-proxyproto/issues/65Issue Tracking, Third Party Advisory
https://github.com/pires/go-proxyproto/pull/74Patch, Third Party Advisory
https://github.com/pires/go-proxyproto/pull/74/commits/cdc63867da24fc609b727231f682670d0d1cd346Patch, Third Party Advisory
https://github.com/pires/go-proxyproto/releases/tag/v0.6.0Release Notes, Third Party Advisory
https://snyk.io/vuln/SNYK-GOLANG-GITHUBCOMPIRESGOPROXYPROTO-1316439Patch, Third Party Advisory

Timeline

Published: Jul 21, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-23409?

The package github.com/pires/go-proxyproto before 0.6.0 are vulnerable to Denial of Service (DoS) via creating connections without the proxy protocol header.

How severe is CVE-2021-23409?

CVE-2021-23409 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.65% probability of exploitation in the next 30 days.

How do I fix CVE-2021-23409?

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-2021-23409?

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

Scan your code now

Source: NVD / NIST