Ruby

By the Year

In 2026 there have been 8 vulnerabilities in Ruby with an average score of 8.1 out of ten. Last year, in 2025 Ruby had 2 security vulnerabilities published. That is, 6 more vulnerabilities have already been reported in 2026 as compared to last year.

Recent Ruby Security Vulnerabilities

CVE	Date	Vulnerability	Products
CVE-2026-42258	May 09, 2026	CRLF Injection CVE-2026-42258 in Ruby Net::IMAP <0.6.4 via Symbol args 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, symbol arguments to commands are vulnerable to a CRLF Injection / IMAP Command injection via Symbol arguments passed to IMAP commands. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.
CVE-2026-42257	May 09, 2026	Net::IMAP RCE: IMAP Command Injection via CRLF (Ruby <=0.6.4) 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.
CVE-2026-42256	May 09, 2026	CVE-2026-42256: DoS in Ruby Net::IMAP <0.4.24/0.5.14/0.6.4 via SCRAM Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile server can perform a computational denial-of-service attack on the client process by sending a big iteration count value. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.
CVE-2026-42245	May 09, 2026	Net::IMAP Quadratic ResponseReader DoS (0.4.23, 0.5.13, 0.6.3) Ruby 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, Net::IMAP::ResponseReader has quadratic time complexity when reading large responses containing many string literals. A hostile server can send responses which are crafted to exhaust the client's CPU for a denial of service attack. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.
CVE-2026-42246	May 09, 2026	Ruby Net::IMAP <=0.6.4 MITM Without TLS on starttls Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.3.10, 0.4.24, 0.5.14, and 0.6.4, a man-in-the-middle attacker can cause Net::IMAP#starttls to return "successfully", without starting TLS. This issue has been patched in versions 0.3.10, 0.4.24, 0.5.14, and 0.6.4.
CVE-2026-41316	Apr 24, 2026	Ruby ERB <4.0.3.1 / <4.0.4.1 / <6.0.1.1 Exploitable via Marshal.load ERB is a templating system for Ruby. Ruby 2.7.0 (before ERB 2.2.0 was published on rubygems.org) introduced an `@_init` instance variable guard in `ERB#result` and `ERB#run` to prevent code execution when an ERB object is reconstructed via `Marshal.load` (deserialization). However, three other public methods that also evaluate `@src` via `eval()` were not given the same guard: `ERB#def_method`, `ERB#def_module`, and `ERB#def_class`. An attacker who can trigger `Marshal.load` on untrusted data in a Ruby application that has `erb` loaded can use `ERB#def_module` (zero-arg, default parameters) as a code execution sink, bypassing the `@_init` protection entirely. ERB 4.0.3.1, 4.0.4.1, 6.0.1.1, and 6.0.4 patch the issue.
CVE-2026-27820	Apr 16, 2026	Ruby zlib Buffer Overflow in GzipReader (3.2.1) zlib is a Ruby interface for the zlib compression/decompression library. Versions 3.0.0 and below, 3.1.0, 3.1.1, 3.2.0 and 3.2.1 contain a buffer overflow vulnerability in the Zlib::GzipReader. The zstream_buffer_ungets function prepends caller-provided bytes ahead of previously produced output but fails to guarantee the backing Ruby string has enough capacity before the memmove shifts the existing data. This can lead to memory corruption when the buffer length exceeds capacity. This issue has been fixed in versions 3.0.1, 3.1.2 and 3.2.3.
CVE-2026-33210	Mar 20, 2026	Ruby JSON 2.14.0-2.15.2.1 Format String Injection (allow_duplicate_key: false) Ruby JSON is a JSON implementation for Ruby. From version 2.14.0 to before versions 2.15.2.1, 2.17.1.2, and 2.19.2, a format string injection vulnerability can lead to denial of service attacks or information disclosure, when the allow_duplicate_key: false parsing option is used to parse user supplied documents. This issue has been patched in versions 2.15.2.1, 2.17.1.2, and 2.19.2.
CVE-2025-61594	Dec 30, 2025	URI is a module providing classes to handle Uniform Resource Identifiers URI is a module providing classes to handle Uniform Resource Identifiers. In versions 0.12.4 and earlier (bundled in Ruby 3.2 series) 0.13.2 and earlier (bundled in Ruby 3.3 series), 1.0.3 and earlier (bundled in Ruby 3.4 series), when using the + operator to combine URIs, sensitive information like passwords from the original URI can be leaked, violating RFC3986 and making applications vulnerable to credential exposure. This is a a bypass for the fix to CVE-2025-27221 that can expose user credentials. This issue has been fixed in versions 0.12.5, 0.13.3 and 1.0.4.
CVE-2025-58767	Sep 17, 2025	REXML DoS: Multiple XML Declarations 3.3.3–3.4.1 REXML is an XML toolkit for Ruby. The REXML gems from 3.3.3 to 3.4.1 has a DoS vulnerability when parsing XML containing multiple XML declarations. If you need to parse untrusted XMLs, you may be impacted to these vulnerabilities. The REXML gem 3.4.2 or later include the patches to fix these vulnerabilities.	Rexml