Full authentication bypass if SASL authorization username is specified (CVE-2023-27582) | HOL Guard CVE

Critical · CVSS 9.1CVE-2023-27582GHSA-4G76-W3XW-2X6W

Full authentication bypass if SASL authorization username is specified

Answer in brief

CVE-2023-27582 records a Critical severity (CVSS 9.1) vulnerability in Full authentication bypass if SASL authorization username is specified. The current sources do not mark it as known exploited. The current feed maps github.com/foxcpp/maddy (go). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Mar 14, 2023Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Sep 10, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: Critical · CVSS 9.1
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 9.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps github.com/foxcpp/maddy (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
github.com/foxcpp/maddygo	>=0.2.0 <0.6.3	0.6.3

Recommended response

Check inventory. Check lockfiles and deployed manifests for github.com/foxcpp/maddy.
Review the reported fix. Update github.com/foxcpp/maddy to 0.6.3 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Mar 14, 2023
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

### 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

Quoted source text, attributed separately from HOL analysis.