Medium 5.9Published Dec 7, 2017

CVE-2017-3737OpenSSL 1.0.2 (starting from version 1.0.2b) introduced an "error state" mechanism.

Updated under an hour ago (Nov 2, 2026, 12:10 AM ET)

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No exploitation reported and no EPSS estimate yet.

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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.

CVSS: 5.9 MEDIUM (v3.0, NVD)CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE): CWE-125, CWE-787
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Modified
Record last updated: Jun 16, 2026
First seen by InfoSec Signals: Nov 1, 2026

Affected products

Affected products

openssl openssl openssl:openssl	1.0.2b; 1.0.2c; 1.0.2d; 1.0.2e; 1.0.2f; 1.0.2g; 1.0.2h; 1.0.2i; and 4 more ranges	NVD
debian debian_linux debian:debian_linux	9.0	NVD

References

References

http://www.oracle.com/technetwork/security-advisory/cpuapr2018-3678067.html
http://www.oracle.com/technetwork/security-advisory/cpujan2018-3236628.html
http://www.oracle.com/technetwork/security-advisory/cpujul2018-4258247.html
http://www.securityfocus.com/bid/102103	third-party-advisory, vdb-entry
http://www.securitytracker.com/id/1039978	third-party-advisory, vdb-entry
https://access.redhat.com/errata/RHSA-2018:0998
https://access.redhat.com/errata/RHSA-2018:2185
https://access.redhat.com/errata/RHSA-2018:2186
https://access.redhat.com/errata/RHSA-2018:2187
https://cert-portal.siemens.com/productcert/pdf/ssa-179516.pdf
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