Answer in brief
CVE-2019-16791 records a Medium severity (CVSS 6.9) vulnerability in postfix-mta-sts-resolver Algorithm Downgrade vulnerability. The current sources do not mark it as known exploited. The current feed maps postfix-mta-sts-resolver (pypi). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.9. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps postfix-mta-sts-resolver (pypi). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| postfix-mta-sts-resolverpypi | >=0 <0.5.1 | 0.5.1 |
Published upstream
Jul 5, 2019
Evidence: source:osv:source_dates:source-dates:recordSource modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:recordFirst seen by HOL
Sep 10, 2026
## Incorrect query parsing ### Impact All users of versions prior to 0.5.1 can receive incorrect response from daemon under rare conditions, rendering downgrade of effective STS policy. ### Patches Problem has been patched in version 0.5.1 ### Workarounds Users may remediate this vulnerability without upgrading by applying [these patches](https://gist.github.com/Snawoot/b9da85d6b26dea5460673b29df1adc6b) to older suppoorted versions. ### For more information If you have any questions or comments about this advisory: * Open an issue in [postfix-mta-sts-resolver repo](https://github.com/Snawoot/postfix-mta-sts-resolver) * Email me at [vladislav at vm-0 dot com](mailto:[email protected])
Quoted source text, attributed separately from HOL analysis.