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Fencer Vulns
high 7.5

CVE-2021-23409 json

Denial of Service (DoS)

published 2021-07-21 5 y ago modified 2026-09-10 1 mo ago also GHSA-xcf7-q56x-78gh , GO-2022-0233 , EUVD-2021-1500

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 76%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/pires/go-proxyproto 0.6.1
  • n/a github.com/pires/go-proxyproto 0.6.0
  • golang-github-pires-go-proxyproto Debian 14, Debian 13, Debian 12 0.4.2-2

debian advisories DEBIAN-CVE-2021-23409

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-23409 updated cvss 7.5

golang-github-pires-proxyproto: DoS via creating connections without the proxy protocol header

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.65% chance of exploitation in the next 30 days, higher than 76% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
go github.com/pires/go-proxyproto
<0.6.1
0.6.1

Affected products

  • n/a github.com/pires/go-proxyproto

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.