{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-46428","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-05-13T22:18:22.830Z","datePublished":"2026-07-20T15:37:58.396Z","dateUpdated":"2026-07-21T15:49:36.495Z"},"containers":{"cna":{"title":"lettre has TLS hostname verification disabled when using Boring TLS backend","problemTypes":[{"descriptions":[{"cweId":"CWE-295","lang":"en","description":"CWE-295: Improper Certificate Validation","type":"CWE"}]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"LOW","subIntegrityImpact":"LOW","subAvailabilityImpact":"NONE","baseScore":9.1,"baseSeverity":"CRITICAL","vectorString":"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","version":"4.0"}}],"references":[{"name":"https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53","tags":["x_refsource_CONFIRM"],"url":"https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53"},{"name":"https://github.com/lettre/lettre/commit/f5efffc88360dbdbfcef80f465e42d5bce68ca35","tags":["x_refsource_MISC"],"url":"https://github.com/lettre/lettre/commit/f5efffc88360dbdbfcef80f465e42d5bce68ca35"},{"name":"https://github.com/lettre/lettre/releases/tag/v0.11.22","tags":["x_refsource_MISC"],"url":"https://github.com/lettre/lettre/releases/tag/v0.11.22"},{"name":"https://rustsec.org/advisories/RUSTSEC-2026-0141.html","tags":["x_refsource_MISC"],"url":"https://rustsec.org/advisories/RUSTSEC-2026-0141.html"}],"affected":[{"vendor":"lettre","product":"lettre","versions":[{"version":">= 0.10.1, < 0.11.22","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-07-20T15:37:58.396Z"},"descriptions":[{"lang":"en","value":"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."}],"source":{"advisory":"GHSA-4pj9-g833-qx53","discovery":"UNKNOWN"}},"adp":[{"references":[{"url":"https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-21T15:48:51.405919Z","id":"CVE-2026-46428","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-07-21T15:49:36.495Z"}}]}}