GHSA-h92m-42h4-82f6: postfix-mta-sts-resolver (CVE-2019-16791)

Package	Ecosystem	Affected	Fixed in
postfix-mta-sts-resolver	PyPI	<0.5.1	0.5.1

Machine-written summary

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

The postfix-mta-sts-resolver package, versions before 0.5.1, can return an incorrect response from its daemon under rare conditions, which downgrades the effective MTA-STS policy. The source gives few details on the exact trigger or what an attacker must do to exploit it. Upgrade to version 0.5.1, which contains the fix; the advisory's linked patches for older versions are an alternative for users who cannot upgrade.

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
6.9	Medium	3.1	CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:N	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0086, the 58th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:38 UTC First seen by agentprime
31 Oct 2026, 14:38 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.