ruby net-imap up to 0.4.23/0.5.13/0.6.3 Net::IMAP crlf injection

Summaryinfo

A vulnerability classified as problematic has been found in ruby net-imap up to 0.4.23/0.5.13/0.6.3. Affected by this issue is the function Net::IMAP. This manipulation causes crlf injection. This vulnerability appears as CVE-2026-42257. The attack requires local access. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in ruby net-imap up to 0.4.23/0.5.13/0.6.3. It has been declared as problematic. Affected by this vulnerability is the function Net::IMAP. 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 integrity. The summary by CVE is:

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, several Net::IMAP commands accept a raw string argument that is sent to the server without validation or escaping. If this string is derived from user-controlled input, it may contain contain CRLF sequences, which an attacker can use to inject arbitrary IMAP commands. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-42257 since 04/26/2026. The exploitation appears to be easy. An attack has to be approached locally. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 321185 (Ubuntu 16.04 LTS / 18.04 LTS : Ruby vulnerabilities (USN-8431-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 0.4.24, 0.5.14 or 0.6.4 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the databases at Tenable (321185) and CERT Bund (WID-SEC-2026-2117). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

• Red Hat Enterprise Linux
• RESF Rocky Linux
• HCL BigFix
• Oracle Linux

Productinfo

Type

• Programming Language Software

Vendor

• ruby

Name

• net-imap

Version

• 0.4.0
• 0.4.1
• 0.4.2
• 0.4.3
• 0.4.4
• 0.4.5
• 0.4.6
• 0.4.7
• 0.4.8
• 0.4.9
• 0.4.10
• 0.4.11
• 0.4.12
• 0.4.13
• 0.4.14
• 0.4.15
• 0.4.16
• 0.4.17
• 0.4.18
• 0.4.19
• 0.4.20
• 0.4.21
• 0.4.22
• 0.4.23
• 0.5.0
• 0.5.1
• 0.5.2
• 0.5.3
• 0.5.4
• 0.5.5
• 0.5.6
• 0.5.7
• 0.5.8
• 0.5.9
• 0.5.10
• 0.5.11
• 0.5.12
• 0.5.13
• 0.6.0
• 0.6.1
• 0.6.2
• 0.6.3

License

• open-source

Website

• Product: https://github.com/ruby/net-imap/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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