Ruby up to 2.3.x SMTP Net::SMTP crlf injection

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.

A vulnerability was found in Ruby up to 2.3.x (Programming Language Software). It has been declared as critical. Affected by this vulnerability is the function Net::SMTP of the component SMTP Handler. The manipulation with an unknown input leads to a crlf injection vulnerability. The CWE definition for the vulnerability is CWE-93. The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Net::SMTP in Ruby before 2.4.0 is vulnerable to SMTP command injection via CRLF sequences in a RCPT TO or MAIL FROM command, as demonstrated by CRLF sequences immediately before and after a DATA substring.

The bug was discovered 12/11/2015. The weakness was disclosed 06/12/2017 (Website). It is possible to read the advisory at This vulnerability is known as CVE-2015-9096 since 06/12/2017. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability was handled as a non-public zero-day exploit for at least 549 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 101974 (Ubuntu 14.04 LTS / 16.04 LTS / 17.04 : ruby1.9.1, ruby2.0, ruby2.3 vulnerabilities (USN-3365-1)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Ubuntu Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 196859 (Ubuntu Security Notification for Ruby1.9.1, Ruby2.0, Ruby2.3 Vulnerabilities (USN-3365-1)).

Upgrading to version 2.4.0 eliminates this vulnerability. A possible mitigation has been published 2 months after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (101974).






CPE 2.3info

CPE 2.2info


VulDB CVSS-B Score: 🔍
VulDB CVSS-BT Score: 🔍
VulDB Vector: 🔍
VulDB Reliability: 🔍


VulDB Meta Base Score: 6.7
VulDB Meta Temp Score: 6.6

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 6.1
NVD Vector: 🔍



VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍


Class: Crlf injection
CWE: CWE-93 / CWE-74 / CWE-707

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍


Nessus ID: 101974
Nessus Name: Ubuntu 14.04 LTS / 16.04 LTS / 17.04 : ruby1.9.1, ruby2.0, ruby2.3 vulnerabilities (USN-3365-1)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 841810
OpenVAS Name: Ubuntu Update for ruby2.3 USN-3365-1
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍


Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Upgrade: Ruby 2.4.0


12/11/2015 🔍
06/12/2017 +549 days 🔍
06/12/2017 +0 days 🔍
06/12/2017 +0 days 🔍
06/13/2017 +1 days 🔍
07/25/2017 +42 days 🔍
07/26/2017 +1 days 🔍
12/08/2022 +1961 days 🔍


Advisory: USN-3365-1
Status: Not defined

CVE: CVE-2015-9096 (🔍)


Created: 06/13/2017 08:51 AM
Updated: 12/08/2022 12:29 PM
Changes: 06/13/2017 08:51 AM (77), 10/16/2019 10:32 AM (2), 12/08/2022 12:15 PM (5), 12/08/2022 12:22 PM (1), 12/08/2022 12:29 PM (1)
Complete: 🔍
Cache ID: 35:064:40


No comments yet. Languages: en.

Please log in to comment.

Interested in the pricing of exploits?

See the underground prices here!