CVE-2026-123612 · Package
NO FIX YET · SEE WHAT TO DO
rustls 0.23.44 and 0.23.45 send application data queued before the handshake completes to the public_name server when Encrypted Client Hello is rejected. The authenticated public-facing server, not the intended inner server, receives data meant for the inner server, which can leak it.
first public Oct 14, 2026 · 1 source
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Applications using rustls 0.23.44 or 0.23.45 as a TLS client with Encrypted Client Hello configured can send early plaintext to the public_name server when ECH is rejected. Clients that do not use ECH, and servers using rustls, are not described as affected by the sources.
Not affected if no-ech, other-rustls-version
Who cares ech, rust, rustls, tls
Cargo.lock for rustls 0.23.44 or 0.23.45rustls past 0.23.45 (the sources do not name the fixed version)rustls 0.23.44 and 0.23.45 contain an information disclosure vulnerability that sends application data buffered before the handshake completes to the client-facing server when Encrypted Client Hello is rejected. Because start_traffic() queues plaintext from ClientConnection::writer() before sending the ech_required alert, the authenticated public_name server receives data intended for the inner server.
This page as .md · .json · CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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