CVE-2025-61594: Ruby-lang Uri Information Disclosure Bug

CVE-2025-61594 Overview

CVE-2025-61594 is an information disclosure vulnerability in the Ruby URI module that can expose user credentials. This vulnerability represents a bypass of the fix for CVE-2025-27221, allowing sensitive information such as passwords from the original URI to leak when using the + operator to combine URIs. The flaw violates RFC3986 specifications and makes applications vulnerable to credential exposure.

Critical Impact

Applications using vulnerable versions of the Ruby URI module may inadvertently expose user credentials when combining URIs using the + operator, potentially leading to unauthorized access.

Affected Products

• ruby-lang uri versions prior to 0.12.5
• ruby-lang uri versions prior to 0.13.3
• ruby-lang uri versions prior to 1.0.4

Discovery Timeline

• December 30, 2025 - CVE-2025-61594 published to NVD
• February 24, 2026 - Last updated in NVD database

Technical Details for CVE-2025-61594

Vulnerability Analysis

This vulnerability stems from improper data removal before storage or transfer (CWE-212). When the Ruby URI module's + operator is used to combine two URI objects, sensitive credential information from the original URI can leak into the resulting combined URI. This represents a bypass of a previous security fix implemented for CVE-2025-27221.

The issue specifically impacts how the URI module handles the userinfo component of URIs during concatenation operations. According to RFC3986, the userinfo subcomponent may contain sensitive authentication data that should be properly sanitized during URI manipulation operations to prevent unintended credential disclosure.

Root Cause

The root cause lies in the incomplete handling of userinfo components during URI concatenation operations. When the + operator combines URIs, the implementation fails to properly strip or sanitize password information from the source URI before creating the resulting combined URI. This allows credentials embedded in the original URI's userinfo section to persist and potentially be exposed in logs, error messages, or transmitted to unintended destinations.

Attack Vector

An attacker could exploit this vulnerability in scenarios where applications:

1. Process URIs containing embedded credentials (e.g., scheme://user:password@host/path)
2. Use the + operator to combine or modify these URIs
3. Log, transmit, or otherwise expose the resulting combined URI

The vulnerability requires that an application already handles URIs with embedded credentials and uses the + operator for URI manipulation. The leaked credentials could then be harvested from application logs, network traffic, or error responses where the combined URI is exposed.

Detection Methods for CVE-2025-61594

Indicators of Compromise

• Review application logs for URIs containing unexpected userinfo components (credentials) after URI concatenation operations
• Monitor for unusual authentication attempts using credentials that may have been exposed through URI handling
• Check for the presence of vulnerable URI gem versions (< 0.12.5, < 0.13.3, < 1.0.4) in Ruby application dependencies

Detection Strategies

• Implement static code analysis to identify usage of the URI + operator with URIs that may contain credentials
• Use dependency scanning tools (e.g., Bundler Audit, Dependabot) to detect vulnerable versions of the URI gem
• Review code paths that handle URI construction and manipulation for potential credential exposure

Monitoring Recommendations

• Enable detailed logging for authentication-related events to detect potential credential misuse
• Monitor for anomalous access patterns that could indicate compromised credentials
• Implement alerting on dependency vulnerability scans that flag outdated URI gem versions

How to Mitigate CVE-2025-61594

Immediate Actions Required

• Upgrade the Ruby URI gem to a patched version: 0.12.5, 0.13.3, or 1.0.4 depending on your version branch
• Audit application code for usage of the URI + operator with URIs containing credentials
• Review application logs for potential credential exposure incidents
• Consider rotating any credentials that may have been exposed through vulnerable URI operations

Patch Information

The Ruby-lang team has released patched versions that address this vulnerability. The following commits contain the security fixes:

• Commit 20157e3 - Fix for version 0.12.x branch
• Commit 7e521b2 - Fix for version 0.13.x branch
• Commit d3116ca - Fix for version 1.0.x branch

For detailed information, refer to the Ruby-lang Security Announcement and the RubySec Advisory Database.

Workarounds

• Avoid using the + operator with URI objects that contain embedded credentials until the patch is applied
• Strip credentials from URIs before performing concatenation operations
• Use alternative URI manipulation methods that do not trigger the vulnerable code path

# Update URI gem to patched version
gem update uri

# Or specify minimum version in Gemfile
# gem 'uri', '>= 1.0.4'
bundle update uri