GHSA-4g76-w3xw-2x6w: github.com/foxcpp/maddy (CVE-2023-27582)

Package	Ecosystem	Affected	Fixed in
github.com/foxcpp/maddy	Go	>=0.2.0, <0.6.3	0.6.3

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

maddy versions 0.2.0 through 0.6.2 are affected. When the SASL PLAIN mechanism is used with an authorization username specified, the server does not validate that username after checking the authentication credentials, so an attacker with valid credentials for any account can authenticate as another user, bypassing authentication. Upgrade to maddy 0.6.3, which fixes the issue; the source lists no workaround other than upgrading.

Written 5 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
9.1	Critical	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.010, the 63rd percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:43 UTC First seen by agentprime
31 Oct 2026, 14:43 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.