Back to overview

CVE-2026-46428

CRITICAL
9.1
CVSS 4.0
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.

Metadata

CVE ID
CVE-2026-46428
State
PUBLISHED
Assigner
GitHub_M
Reserved
2026-05-13 22:18 UTC
Published
2026-07-20 15:37 UTC
Last updated
2026-07-20 15:37 UTC
Primary CWE
CWE-295
CWE-295: Improper Certificate Validation
Vendor / Product
lettre / lettre
Sources
cve.org  ·  NVD

Severity & Metrics

9.1 CRITICAL CVSS 4.0
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
Affected products (1)
VendorProductPlatformVersions
lettre lettre — >= 0.10.1, < 0.11.22
Weakness (CWE)
CWESourceDescription
CWE-295 cna CWE-295: Improper Certificate Validation
CVSS scores (1)
ScoreSeverityVersionSourceVector
9.1 CRITICAL 4.0 cna 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 (4)
Back to overview