{"cve":"CVE-2026-46428","nvd":{"published":"2026-07-20T16:17:01.347","modified":"2026-07-23T17:58:34.990","status":"Deferred","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.","cvss_v4":{"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","score":9.1},"cvss_v3":null,"cwes":["CWE-295"],"references":["https://github.com/lettre/lettre/commit/f5efffc88360dbdbfcef80f465e42d5bce68ca35","https://github.com/lettre/lettre/releases/tag/v0.11.22","https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53","https://rustsec.org/advisories/RUSTSEC-2026-0141.html","https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:45:36.895656543+00:00"},"epss":{"cve":"CVE-2026-46428","score":0.00319,"percentile":0.24934,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-4pj9-g833-qx53","url":"https://osv.dev/vulnerability/GHSA-4pj9-g833-qx53","summary":"lettre has TLS hostname verification disabled when using Boring TLS backend","modified":"2026-07-28T14:45:27.676971366Z","packages":[{"ecosystem":"crates.io","name":"lettre","purl":"pkg:cargo/lettre","ranges":[">=0.10.1 <0.11.22"],"fixed":["0.11.22"]}]},{"id":"RUSTSEC-2026-0141","url":"https://osv.dev/vulnerability/RUSTSEC-2026-0141","summary":"TLS hostname verification disabled when using Boring TLS backend","modified":"2026-10-12T18:00:14.045169536Z","packages":[{"ecosystem":"crates.io","name":"lettre","purl":"pkg:cargo/lettre","ranges":[">=0.10.1 <0.11.22"],"fixed":["0.11.22"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}