How severe is CVE-2023-27582?

CVE-2023-27582 has a CVSS score of 9.1/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2023-27582?

CVE-2023-27582 affects the following packages: github.com/foxcpp/maddy (Go). Ecosystems affected: Go.

How do I fix CVE-2023-27582?

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.

How do I detect CVE-2023-27582 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/foxcpp/maddy, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2023-27582 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2023-27582 actively exploited in the wild?

No public exploit code has been indexed for CVE-2023-27582 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2023-27582?

CVE-2023-27582 has an EPSS (Exploit Prediction Scoring System) score of 1.0%, placing it in the 63th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2023-27582?

CVE-2023-27582 is classified as Improper Authentication (CWE-287), CWE-305 (CWE-305). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2023-27582 published, and has it been updated?

CVE-2023-27582 was published on March 13, 2023 and was last updated on August 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

CRITICAL severity

CVE-2023-27582 — maddy

CRITICALFix: foxcpp/maddy@55a91a3

CVE-2023-27582 is a critical-severity (CVSS 9.1) Improper Authentication vulnerability in github.com/foxcpp/maddy. A fix is available for github.com/foxcpp/maddy — see the affected versions and patch details below.

Full authentication bypass if SASL authorization username is specified

Also known asGHSA-4g76-w3xw-2x6wGO-2023-1630

Published

Mar 13, 2023

Updated

Aug 12, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 14, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2023-27582.

EPSS Exploitation Probability

via FIRST.org ↗

1.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs63th percentile — riskier than 63% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2023-27582 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 388,997 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🐹github.com/foxcpp/maddy

Real-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

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

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/foxcpp/maddy`	≥ 0.2.0&&< 0.6.3	0.6.3`go get github.com/foxcpp/maddy@v0.6.3`

Affected Products

1 product · 1 configurations

Application

maddymaddy_project

≥ 0.2.0 && < 0.6.3

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/foxcpp/maddy, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### 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