Summary
Path Traversal in Action View
File Content Disclosure in Action View
Impact
There is a possible file content disclosure vulnerability in Action View. Specially crafted accept headers in combination with calls to render file: can cause arbitrary files on the target server to be rendered, disclosing the file contents.
The impact is limited to calls to render which render file contents without a specified accept format. Impacted code in a controller looks something like this:
class UserController < ApplicationController
def index
render file: "#{Rails.root}/some/file"
end
end
Rendering templates as opposed to files is not impacted by this vulnerability.
All users running an affected release should either upgrade or use one of the workarounds immediately.
Releases
The 6.0.0.beta3, 5.2.2.1, 5.1.6.2, 5.0.7.2, and 4.2.11.1 releases are available at the normal locations.
Workarounds
This vulnerability can be mitigated by specifying a format for file rendering, like this:
class UserController < ApplicationController
def index
render file: "#{Rails.root}/some/file", formats: [:html]
end
end
In summary, impacted calls to render look like this:
render file: "#{Rails.root}/some/file"
The vulnerability can be mitigated by changing to this:
render file: "#{Rails.root}/some/file", formats: [:html]
Other calls to render are not impacted.
Alternatively, the following monkey patch can be applied in an initializer:
$ cat config/initializers/formats_filter.rb
# frozen_string_literal: true
ActionDispatch::Request.prepend(Module.new do
def formats
super().select do |format|
format.symbol || format.ref == "*/*"
end
end
end)
Credits
Thanks to John Hawthorn [email protected] of GitHub
Impact
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2019-5418 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.1.6.2, 5.0.7.2, 5.2.2.1, 4.2.11.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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actionview to 5.1.6.2 or later; actionview to 5.0.7.2 or later; actionview to 5.2.2.1 or later; actionview to 4.2.11.1 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2019-5418? CVE-2019-5418 is a high-severity path traversal vulnerability in actionview (rubygems), affecting versions >= 5.1.0, <= 5.1.6.1. It is fixed in 5.1.6.2, 5.0.7.2, 5.2.2.1, 4.2.11.1. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- How severe is CVE-2019-5418? CVE-2019-5418 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of actionview are affected by CVE-2019-5418? actionview (rubygems) versions >= 5.1.0, <= 5.1.6.1 is affected.
- Is there a fix for CVE-2019-5418? Yes. CVE-2019-5418 is fixed in 5.1.6.2, 5.0.7.2, 5.2.2.1, 4.2.11.1. Upgrade to this version or later.
- Is CVE-2019-5418 exploitable, and should I be worried? Whether CVE-2019-5418 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2019-5418 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2019-5418?
- Upgrade
actionviewto 5.1.6.2 or later - Upgrade
actionviewto 5.0.7.2 or later - Upgrade
actionviewto 5.2.2.1 or later - Upgrade
actionviewto 4.2.11.1 or later
- Upgrade