CVE-2026-46428
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
Summary
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.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| lettre | lettre | >= 0.10.1, < 0.11.22 | affected |
Weaknesses
- CWE-295: CWE-295: Improper Certificate Validation
References
- https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53
- https://github.com/lettre/lettre/commit/f5efffc88360dbdbfcef80f465e42d5bce68ca35
- https://github.com/lettre/lettre/releases/tag/v0.11.22
- https://rustsec.org/advisories/RUSTSEC-2026-0141.html
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