CVE-2023-27582 is a critical-severity (CVSS 9.1) Improper Authentication vulnerability in github.com/foxcpp/maddy. O3 Security confirms whether CVE-2023-27582 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Full authentication bypass if SASL authorization username is specified
Real-World Exposure
github.com/foxcpp/maddyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
maddy is a composable, all-in-one mail server. Starting with version 0.2.0 and prior to version 0.6.3, maddy allows a full authentication bypass if SASL authorization username is specified when using the PLAIN authentication mechanisms. Instead of validating the specified username, it is accepted as is after checking the credentials for the authentication username. maddy 0.6.3 includes the fix for the bug. There are no known workarounds.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/foxcpp/maddy | ≥ 0.2.0&&< 0.6.3 | 0.6.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/foxcpp/maddy. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/foxcpp/maddy to 0.6.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-27582 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2023-27582 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2023-27582. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-27582 in your dependencies?
O3 detects CVE-2023-27582 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.