OpenSSL CVE-2017-3737 Out of Bounds Read Vulnerability

Description

Severity: ModerateOpenSSL 1.0.2 (starting from version 1.0.2b) introduced an "error state"mechanism. The intent was that if a fatal error occurred during a handshake thenOpenSSL would move into the error state and would immediately fail if youattempted to continue the handshake. This works as designed for the explicithandshake functions (SSL_do_handshake(), SSL_accept() and SSL_connect()),however due to a bug it does not work correctly if SSL_read() or SSL_write() iscalled directly. In that scenario, if the handshake fails then a fatal errorwill be returned in the initial function call. If SSL_read()/SSL_write() issubsequently called by the application for the same SSL object then it willsucceed and the data is passed without being decrypted/encrypted directly fromthe SSL/TLS record layer.In order to exploit this issue an application bug would have to be present thatresulted in a call to SSL_read()/SSL_write() being issued after having alreadyreceived a fatal error.This issue does not affect OpenSSL 1.1.0.OpenSSL 1.0.2 users should upgrade to 1.0.2nThis issue was reported to OpenSSL on 10th November 2017 by David Benjaminof the OpenSSL development team.

Affected Applications

OpenSSL

CVE References

Other References