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CVE-2019-16791

20
FAUCET Score

CVE-2019-16791 affects postfix-mta-sts-resolver versions prior to 0.5.1, where a rare condition can lead to users receiving incorrect responses from the daemon. This vulnerability, rated Medium with a CVSS score of 5.9, allows for a downgrade of the effective STS policy, potentially impacting email security. The attack vector is network-based with high attack complexity, but it does not require user interaction or privileges, and its primary impact is on availability. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.5.1CPE matchmatch criteria
cpe:2.3:a:postfix-mta-sts-resolver_project:postfix-mta-sts-resolver:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.9MEDIUM

CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:N

Attack Vector
LOCAL
Attack Complexity
HIGH
Privileges Required
HIGH
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
0.6
Impact Score
5.8
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.78%
Probability of exploitation in next 30 days
EPSS Percentile
52.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0078 is in the 11th percentile among its peer group of 19,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: postfix-mta-sts-resolverFixed in: 0.5.1

Vendor Advisories (1)

pipGHSA-h92m-42h4-82f6high

postfix-mta-sts-resolver Algorithm Downgrade vulnerability

Jul 5, 2019

References

gist.github.com / Snawoot/b9da85d6b26dea5460673b29df1adc6b
PatchThird Party Advisory
github.com / Snawoot/postfix-mta-sts-resolver/security/advisories/GHSA-h92m-42h4-82f6
PatchThird Party Advisory