CVE-2026-46428None▾ SunlitTLS hostname verification disabled when using Boring TLS backend
▾ Sunlit zone — Low / medium · no exploitation signal
impact 2.8 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Jul 21.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
Last analysed / modified upstream
0.2%
0.2% → 0.3%
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.
The bug was introduced in v0.10.1 and persists through v0.11.21 (latest).
lettre >= 0.10.1, < 0.11.22Upgrade to a patched release:
lettre 0.11.22