CVE-2017-3737

Published Dec 7, 2017

Last updated 5 years ago

Overview

Description
OpenSSL 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 then OpenSSL would move into the error state and would immediately fail if you attempted to continue the handshake. This works as designed for the explicit handshake 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() is called directly. In that scenario, if the handshake fails then a fatal error will be returned in the initial function call. If SSL_read()/SSL_write() is subsequently called by the application for the same SSL object then it will succeed and the data is passed without being decrypted/encrypted directly from the SSL/TLS record layer. In order to exploit this issue an application bug would have to be present that resulted in a call to SSL_read()/SSL_write() being issued after having already received a fatal error. OpenSSL version 1.0.2b-1.0.2m are affected. Fixed in OpenSSL 1.0.2n. OpenSSL 1.1.0 is not affected.
Source
openssl-security@openssl.org
NVD status
Modified

Risk scores

CVSS 3.0

Type
Primary
Base score
5.9
Impact score
3.6
Exploitability score
2.2
Vector string
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Severity
MEDIUM

CVSS 2.0

Type
Primary
Base score
4.3
Impact score
2.9
Exploitability score
8.6
Vector string
AV:N/AC:M/Au:N/C:P/I:N/A:N

Weaknesses

nvd@nist.gov
CWE-125

Social media

Hype score
Not currently trending

Configurations