CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:M/Au:N/C:N/I:P/A:N
EPSS
Percentile
49.3%
Security researcher Karthikeyan Bhargavan reported an issue in Network Security Services (NSS) where the client allows for a ECDHE_ECDSA exchange where the server does not send its ServerKeyExchange message instead of aborting the handshake. Instead, the NSS client will take the EC key from the ECDSA certificate. This violates the TLS protocol and also has some security implications for forward secrecy. In this situation, the browser thinks it is engaged in an ECDHE exchange, but has been silently downgraded to a non-forward secret mixed-ECDH exchange instead. As a result, if False Start is enabled, the browser will start sending data encrypted under these non-forward-secret connection keys. This issue was fixed in NSS version 3.19.1.