Out-of-bounds Read Affecting openssl package, versions <1.1.0b-2


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
94.55% (100th percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-OPENSSL-374522
  • published7 Dec 2017
  • disclosed7 Dec 2017

Introduced: 7 Dec 2017

CVE-2017-3737  (opens in a new tab)
CWE-125  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Debian:unstable openssl to version 1.1.0b-2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream openssl package and not the openssl package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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.