---
id: CVE-2023-27582
aliases:
  - GHSA-4g76-w3xw-2x6w
  - GO-2023-1630
title: Full authentication bypass if SASL authorization username is specified
summary: Full authentication bypass if SASL authorization username is specified
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'
vendor: foxcpp
product: github.com/foxcpp/maddy
ecosystem: go
affected:
  - 'github.com/foxcpp/maddy >= 0.2.0, < 0.6.3'
patched:
  - github.com/foxcpp/maddy 0.6.3
published: '2023-03-14'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:49:52.395242124Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-4g76-w3xw-2x6w'
references:
  - url: 'https://github.com/foxcpp/maddy/security/advisories/GHSA-4g76-w3xw-2x6w'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2023-27582'
  - url: >-
      https://github.com/foxcpp/maddy/commit/55a91a37b71210f34f98f4d327c30308fe24399a
  - url: >-
      https://github.com/foxcpp/maddy/commit/9f58cb64b39cdc01928ec463bdb198c4c2313a9c
  - url: 'https://github.com/foxcpp/maddy'
  - url: 'https://github.com/foxcpp/maddy/releases/tag/v0.6.3'
tags:
  - osv
  - go
epss: 0.01019
epssPercentile: 0.61859
ingestedAt: '2026-09-12T03:13:01.752Z'
---

## Overview

### Impact

maddy 0.2.0 - 0.6.2 allows a full authentication bypass if SASL authorization username is specified when using the PLAIN authentication mechanisms. Instead of validating the specified authorization username, it is accepted as is after checking the credentials for the authentication username.

### Patches

maddy 0.6.3 includes the fix for the bug. 

### Workarounds

There is no way to fix the issue without upgrading.

### References

* Commit that introduced the vulnerable code: https://github.com/foxcpp/maddy/commit/55a91a37b71210f34f98f4d327c30308fe24399a
* Fix: https://github.com/foxcpp/maddy/commit/9f58cb64b39cdc01928ec463bdb198c4c2313a9c


## Affected packages

- `github.com/foxcpp/maddy >= 0.2.0, < 0.6.3`

## Remediation

Upgrade to a patched release:

- `github.com/foxcpp/maddy 0.6.3`