CVE-2026-123611
Received
Received - Intake
Key Exchange Downgrade in rustls Library
Vulnerability report for CVE-2026-123611, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-11-08
Last updated on: 2026-11-08
Assigner: VulnCheck
Description
Description
rustls before 0.23.46 contains a key exchange downgrade vulnerability that allows network attackers to poison the per-server-name key-exchange group record via an unauthenticated ServerHello. Attackers can answer one connection with a ServerHello selecting X25519, causing later ClientHellos to send only classical shares and lose post-quantum confidentiality.
CVSS Scores
EPSS Scores
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Meta Information
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-757 | A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties. |
