CVE-2026-123612
rustls 0.23.44 and 0.23.45 ECH Rejection Application Data Disclosure
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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
What each source reports
CVE List Score used
rustls 0.23.44 and 0.23.45 ECH Rejection Application Data Disclosure
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.
- Record
CVE-2026-123612- CVSS 4.0
- 4.6 Medium
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 - CVSS 3.1
- 2.3 Low
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-696
- Updated
- 2026-11-08
EUVDEUVD-2026-119371
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.
- Record
EUVD-2026-119371- CVSS 4.0
- 4.6 Medium
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 - Updated
- 2026-11-08
GitHub AdvisoriesGHSA-jrx3-hh25-gg3m
rustls 0.23.44 and 0.23.45 contain an information disclosure vulnerability that sends application...
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.
- Record
GHSA-jrx3-hh25-gg3m- CVSS 4.0
- 4.6 Medium
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 - CVSS 3.1
- 2.3 Low
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-696
- Updated
- 2026-11-08
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, references | GitHub Advisories | |
| aliases, products, published | EUVD | |
| first indexed | CVE List |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-123612 is a medium vulnerability (CVSS 4.6) in Rustls, published November 8, 2026. No source lists public exploit code. No source names a fixed version.