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CVE-2021-23409

24
FAUCET Score

CVE-2021-23409 describes a Denial of Service (DoS) vulnerability in the github.com/pires/go-proxyproto package prior to version 0.6.0, allowing attackers to disrupt service by creating connections without the expected proxy protocol header. With a CVSS score of 7.5 (HIGH), this vulnerability is easily exploitable over the network with low attack complexity, potentially leading to a complete loss of availability. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.6.0CPE matchmatch criteria
cpe:2.3:a:go-proxyproto_project:go-proxyproto:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.65%
Probability of exploitation in next 30 days
EPSS Percentile
74.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0165 is in the 56th percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
gopatch availablevia ghsa
Product: github.com/pires/go-proxyprotoFixed in: 0.6.1

Vendor Advisories (1)

goGHSA-xcf7-q56x-78ghhigh

github.com/pires/go-proxyproto vulnerable to DoS via Connection descriptor exhaustion

Jul 26, 2021

References

github.com / pires/go-proxyproto/issues/65
Issue TrackingThird Party Advisory
github.com / pires/go-proxyproto/pull/74
PatchThird Party Advisory
github.com / pires/go-proxyproto/pull/74/commits/cdc63867da24fc609b727231f682670d0d1cd346
PatchThird Party Advisory
github.com / pires/go-proxyproto/releases/tag/v0.6.0
Release NotesThird Party Advisory
snyk.io / vuln/SNYK-GOLANG-GITHUBCOMPIRESGOPROXYPROTO-1316439
PatchThird Party Advisory