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CVE-2019-11027

9.8 CRITICAL
Remote Code Execution Authentication Bypass

📋 TL;DR

CVE-2019-11027 is a critical vulnerability in ruby-openid library versions through 2.8.0 that allows remote attackers to execute arbitrary code on affected systems. This affects Ruby on Rails web applications that use this library for OpenID authentication integration. Developers who based their implementation heavily on the project's example application are at highest risk.

💻 Affected Systems

Products:
  • ruby-openid
  • Ruby on Rails applications using ruby-openid
Versions: All versions through 2.8.0
Operating Systems: All operating systems running Ruby applications
Default Config Vulnerable: ⚠️ Yes
Notes: Applications that closely follow the example implementation provided by the ruby-openid project are most vulnerable. Custom implementations may have varying levels of exposure.

📦 What is this software?

Ruby Openid by Openid

View all CVEs affecting Ruby Openid →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete system compromise, data theft, and lateral movement within the network.

🟠

Likely Case

Authentication bypass and potential session hijacking, allowing attackers to impersonate legitimate users.

🟢

If Mitigated

Limited impact with proper input validation and security controls, potentially reduced to denial of service.

🌐 Internet-Facing: HIGH - This vulnerability affects web applications that are typically internet-facing and handle user authentication.
🏢 Internal Only: MEDIUM - Internal applications using this library are still vulnerable but have reduced attack surface.

🎯 Exploit Status

Public PoC: ⚠️ Yes
Weaponized: LIKELY
Unauthenticated Exploit: ⚠️ Yes
Complexity: LOW

The vulnerability is remotely exploitable without authentication. Public proof-of-concept code exists in the GitHub issue tracker.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 2.9.0 and later

Vendor Advisory: https://github.com/openid/ruby-openid/issues/122

Restart Required: Yes

Instructions:

1. Update Gemfile to specify 'gem "ruby-openid", ">= 2.9.0"' 2. Run 'bundle update ruby-openid' 3. Restart the Rails application server 4. Test OpenID authentication functionality

🔧 Temporary Workarounds

Input Validation Workaround

all

Implement strict input validation for OpenID parameters before processing

# Add parameter validation in OpenID controller
# Validate and sanitize all OpenID response parameters
# Reject malformed or suspicious OpenID responses

🧯 If You Can't Patch

  • Implement a web application firewall (WAF) with rules to block malicious OpenID parameter patterns
  • Isolate the vulnerable application behind additional authentication layers and network segmentation

🔍 How to Verify

Check if Vulnerable:

Check Gemfile.lock or run 'bundle show ruby-openid' to see installed version. If version is 2.8.0 or earlier, the system is vulnerable.

Check Version:

bundle show ruby-openid | grep -o '\d\.\d\.\d'

Verify Fix Applied:

After updating, verify version is 2.9.0 or later using 'bundle show ruby-openid'. Test OpenID authentication to ensure functionality remains intact.

📡 Detection & Monitoring

Log Indicators:

  • Unusual OpenID parameter patterns
  • Failed authentication attempts with malformed OpenID responses
  • Error logs containing ruby-openid exceptions

Network Indicators:

  • Suspicious HTTP requests to OpenID callback endpoints with crafted parameters
  • Unusual traffic patterns to authentication endpoints

SIEM Query:

source="application.log" AND "ruby-openid" AND ("error" OR "exception") AND ("parameter" OR "malformed")

📊 Metadata

CVE ID: CVE-2019-11027
CVSS v3 Score: 9.8 (CRITICAL)
CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: June 10, 2019
Last Updated: November 21, 2024

🔗 References

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