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Fencer Intel
medium 4.3

CVE-2011-3187 json

actionpack Improper Input Validation vulnerability

published 2011-08-29 15 y ago modified 2026-06-16 4 mo ago also GHSA-3vfw-7rcp-3xgm , EUVD-2017-0159

cvss
4.3
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
6.7%
EPSS 6.7% chance of exploitation in 30 days, percentile 93%
public exploits
1
Exploit-DB

Summary

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.

Patch / fix

  • rubygems actionpack 2.3.13

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2011-3187 updated cvss 4.3

rubygem-actionpack: does not validate X-Forwarded-For header in requests from class C networks

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. First public exploit (EDB-35352)
  2. Published

Exploit prediction

6.67% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • EDB-35352 Ruby on Rails 3.0.5 - 'WEBrick::HTTPRequest' Module HTTP Header Injection remote, 2011-02-16
  • webservsec.blogspot.com http://webservsec.blogspot.com/2011/02/ruby-on-rails-vulnerability.html referenced PoC, tagged "exploit" by a source, unverified
  • openwall.com http://www.openwall.com/lists/oss-security/2011/08/22/14 referenced PoC, tagged "exploit" by a source, unverified
  • bugzilla.novell.com https://bugzilla.novell.com/show_bug.cgi?id=673010 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected packages

ecosystem package affected fixed in
rubygems actionpack
>=2.3.0, <2.3.13
2.3.13

Classification

Weakness
  • CWE-20 Improper Input Validation
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.