{"id":"GHSA-h92m-42h4-82f6","summary":"postfix-mta-sts-resolver Algorithm Downgrade vulnerability","details":"## Incorrect query parsing\n\n### Impact\nAll users of versions prior to 0.5.1 can receive incorrect response from daemon under rare conditions, rendering downgrade of effective STS policy.\n\n### Patches\nProblem has been patched in version 0.5.1\n\n### Workarounds\nUsers may remediate this vulnerability without upgrading by applying [these patches](https://gist.github.com/Snawoot/b9da85d6b26dea5460673b29df1adc6b) to older suppoorted versions.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [postfix-mta-sts-resolver repo](https://github.com/Snawoot/postfix-mta-sts-resolver)\n* Email me at [vladislav at vm-0 dot com](mailto:vladislav-ex-gh-advisory@vm-0.com)","aliases":["CVE-2019-16791","PYSEC-2020-174"],"modified":"2026-03-13T22:15:44.265354Z","published":"2019-07-05T21:06:58Z","related":["CVE-2019-16791"],"database_specific":{"severity":"HIGH","github_reviewed":true,"cwe_ids":["CWE-757"],"nvd_published_at":null,"github_reviewed_at":"2020-06-16T21:39:43Z"},"references":[{"type":"WEB","url":"https://github.com/Snawoot/postfix-mta-sts-resolver/security/advisories/GHSA-h92m-42h4-82f6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2019-16791"},{"type":"WEB","url":"https://gist.github.com/Snawoot/b9da85d6b26dea5460673b29df1adc6b"},{"type":"PACKAGE","url":"https://github.com/Snawoot/postfix-mta-sts-resolver"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/postfix-mta-sts-resolver/PYSEC-2020-174.yaml"}],"affected":[{"package":{"name":"postfix-mta-sts-resolver","ecosystem":"PyPI","purl":"pkg:pypi/postfix-mta-sts-resolver"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.5.1"}]}],"versions":["0.1.1","0.1.2","0.1.3","0.1.4","0.1.5","0.2.0","0.2.1","0.2.2","0.2.3","0.2.4","0.2.5","0.2.7","0.2.8","0.2.9","0.3.0","0.4.0","0.4.1","0.4.2","0.4.3","0.4.4","0.4.5","0.5.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2019/07/GHSA-h92m-42h4-82f6/GHSA-h92m-42h4-82f6.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:N"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N"}]}