{"id":"CVE-2026-46428","aliases":["GHSA-4pj9-g833-qx53","RUSTSEC-2026-0141"],"url":"https://o3.security/vulnerability/CVE-2026-46428","summary":"lettre has TLS hostname verification disabled when using Boring TLS backend","details":"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.","published":"2026-07-20T15:37:58.396Z","modified":"2026-08-12T03:51:20.542849307Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"lettre","fixedVersion":"0.11.22"}],"fix":{"url":"https://github.com/lettre/lettre/commit/f5efffc88360dbdbfcef80f465e42d5bce68ca35","label":"lettre/lettre@f5efffc"},"references":[{"type":"WEB","url":"https://github.com/lettre/lettre/releases/tag/v0.11.22"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46428.json"},{"type":"ADVISORY","url":"https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-46428"},{"type":"ADVISORY","url":"https://rustsec.org/advisories/RUSTSEC-2026-0141.html"},{"type":"FIX","url":"https://github.com/lettre/lettre/commit/f5efffc88360dbdbfcef80f465e42d5bce68ca35"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:20.542849307Z"}}