--- title: "CVE-2017-3737\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2017-3737?format=md keywords: index, follow --- # CVE-2017-3737 Publication date 7 December 2017 Last updated 25 August 2025 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **5.9 · Medium** [Score breakdown](https://ubuntu.com/security/CVE-2017-3737?format=md#impact-score) Toggle side navigation ## 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. [Read the notes from the security team](https://ubuntu.com/security/CVE-2017-3737?format=md#notes) ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | openssl | 17.10 artful | Fixed 1.0.2g-1ubuntu13.3 | | 17.04 zesty | Fixed 1.0.2g-1ubuntu11.4 | | 16.04 LTS xenial | Fixed 1.0.2g-1ubuntu4.10 | | 14.04 LTS trusty | Not affected | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) * [Patch details](https://ubuntu.com/security/CVE-2017-3737?format=md#patch-details) ## Notes --- ### [leosilva](https://launchpad.net/~leosilva) this issue does not affect OpenSSL 1.1.0 --- ### [mdeslaur](https://launchpad.net/~mdeslaur) 1.0.2b introduced a security hardening mechanism designed to protect against bugs in application code. https://git.openssl.org/?p=openssl.git;a=commit;h=e4f77bf1833245d2b6aa4ce6a16c85e1cdf78589 This CVE applies to the hardening mechanism being incomplete. openssl versions older than 1.0.2b don't have the hardening mechanism at all. ### Patch details For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) | Package | Patch details | | --- | --- | | openssl | * Upstream: * Upstream: | ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 5.9 · Medium * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | High | | Privileges required | None | | User interaction | None | | Scope | Unchanged | | Confidentiality impact | High | | Integrity impact | None | | Availability impact | None | * Scores | Parameter | Value | | --- | --- | | Base score | 5.9 · Medium | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-3737) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2017-3737) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2017-3737) * [Debian](https://security-tracker.debian.org/tracker/CVE-2017-3737) ### Related Ubuntu Security Notices (USN) + [USN-3512-1](https://usn.ubuntu.com/USN-3512-1) + OpenSSL vulnerabilities + 11 December 2017 ### Other references * *