CVE-2017-3737 Other in OpenSSL
Attackers can bypass encryption/decryption if an application calls SSL_read/write after a handshake failure, leading to data exposure or corruption.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2017-3737?
CVE-2017-3737 is a medium-severity vulnerability in Debian Debian Linux, published on 7 Dec 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2017-3737?
It affects 2 products.
Products include Debian Debian Linux, Openssl Openssl.
How do I fix CVE-2017-3737?
Upgrade to a fixed version.
Is CVE-2017-3737 being exploited?
There is no known exploitation of CVE-2017-3737 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as ALPINE-CVE-2017-3737, DEBIAN-CVE-2017-3737, GHSA-fwxf-w2h7-9w25, UBUNTU-CVE-2017-3737.