CVE-2011-3187

CVE-2011-3187 is a medium-severity vulnerability in Rubyonrails Rails with a CVSS 2.0 base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

• Severity: Medium (CVSS 2.0 base score 4.3)
• EPSS exploit prediction: 7% (93rd percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-20
• Affected product: Rubyonrails Rails
• Published: 2011-08-29
• Last modified: 2026-06-16

Description

The to_s method in actionpack/lib/action_dispatch/middleware/remote_ip.rb in Ruby on Rails 3.0.5 does not validate the X-Forwarded-For header in requests from IP addresses on a Class C network, which might allow remote attackers to inject arbitrary text into log files or bypass intended address parsing via a crafted header.

Frequently asked questions

What is CVE-2011-3187?

The to_s method in actionpack/lib/action_dispatch/middleware/remote_ip.rb in Ruby on Rails 3.0.5 does not validate the X-Forwarded-For header in requests from IP addresses on a Class C network, which might allow remote attackers to inject arbitrary text into log files or bypass intended address parsing via a crafted header.

How severe is CVE-2011-3187?

CVE-2011-3187 has a CVSS 2.0 base score of 4.3, rated medium severity.

Is CVE-2011-3187 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2011-3187?

CVE-2011-3187 affects Rubyonrails Rails. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2011-3187?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2011-3187 published?

CVE-2011-3187 was published on 2011-08-29 and last updated on 2026-06-16.

References

• http://archives.neohapsis.com/archives/fulldisclosure/2011-02/0337.html
• http://webservsec.blogspot.com/2011/02/ruby-on-rails-vulnerability.html
• http://www.openwall.com/lists/oss-security/2011/08/17/1
• http://www.openwall.com/lists/oss-security/2011/08/19/11
• http://www.openwall.com/lists/oss-security/2011/08/20/1
• http://www.openwall.com/lists/oss-security/2011/08/22/13
• http://www.openwall.com/lists/oss-security/2011/08/22/14
• http://www.openwall.com/lists/oss-security/2011/08/22/5
• https://bugzilla.novell.com/show_bug.cgi?id=673010

Affected products (1)

• cpe:2.3:a:rubyonrails:rails:3.0.5:*:*:*:*:*:*:*

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