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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-46428 Detail

Description

lettre is a a mailer library for Rust. Starting in version 0.10.1 and prior to version 0.11.22, an inverted-boolean bug in lettre's `boring-tls` integration silently disables TLS hostname verification for callers using the default (strict) configuration. An on-path attacker presenting any chain-valid certificate for any domain can intercept SMTP submission, including PLAIN/LOGIN credentials and message contents, against any lettre user built with the `boring-tls` feature. Other TLS backends (`native-tls`, `rustls`) are unaffected. Version 0.11.22 patches the issue.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

Nist CVSS score does not match with CNA score
CNA:  GitHub, Inc.
CVSS-B 9.1 CRITICAL
Vector:  CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/lettre/lettre/commit/f5efffc88360dbdbfcef80f465e42d5bce68ca35 GitHub, Inc.
https://github.com/lettre/lettre/releases/tag/v0.11.22 GitHub, Inc.
https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53 CISA-ADP, GitHub, Inc.
https://rustsec.org/advisories/RUSTSEC-2026-0141.html GitHub, Inc.

Weakness Enumeration

CWE-ID CWE Name Source
CWE-295 Improper Certificate Validation GitHub, Inc.  

Change History

2 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-46428
NVD Published Date:
07/20/2026
NVD Last Modified:
07/21/2026
Source:
GitHub, Inc.