There is a possible directory traversal and information leak vulnerability in Action View. This was meant to be fixed on CVE-2016-0752. However the 3.2 patch was not covering all possible scenarios. This vulnerability has been assigned the CVE identifier CVE-2016-2097.
Versions Affected: 3.2.x, 4.0.x, 4.1.x
Not affected: 4.2+
Fixed Versions: 3.2.22.2, 4.1.14.2
Impact
Applications that pass unverified user input to the render method in a controller may be vulnerable to an information leak vulnerability.
Impacted code will look something like this:
def index
render params[:id]
end
Carefully crafted requests can cause the above code to render files from unexpected places like outside the application's view directory, and can possibly escalate this to a remote code execution attack.
All users running an affected release should either upgrade or use one of the workarounds immediately.
Releases
The FIXED releases are available at the normal locations.
Workarounds
A workaround to this issue is to not pass arbitrary user input to the render method. Instead, verify that data before passing it to the render method.
For example, change this:
def index
render params[:id]
end
To this:
def index
render verify_template(params[:id])
end
private
def verify_template(name)
# add verification logic particular to your application here
end
Patches
To aid users who aren't able to upgrade immediately we have provided patches for it. It is in git-am format and consist of a single changeset.
- 3-2-render_data_leak_2.patch - Patch for 3.2 series
- 4-1-render_data_leak_2.patch - Patch for 4.1 series
Credits
Thanks to both Jyoti Singh and Tobias Kraze from makandra for reporting this and working with us in the patch!
References
There is a possible directory traversal and information leak vulnerability in Action View. This was meant to be fixed on CVE-2016-0752. However the 3.2 patch was not covering all possible scenarios. This vulnerability has been assigned the CVE identifier CVE-2016-2097.
Versions Affected: 3.2.x, 4.0.x, 4.1.x
Not affected: 4.2+
Fixed Versions: 3.2.22.2, 4.1.14.2
Impact
Applications that pass unverified user input to the
rendermethod in a controller may be vulnerable to an information leak vulnerability.Impacted code will look something like this:
Carefully crafted requests can cause the above code to render files from unexpected places like outside the application's view directory, and can possibly escalate this to a remote code execution attack.
All users running an affected release should either upgrade or use one of the workarounds immediately.
Releases
The FIXED releases are available at the normal locations.
Workarounds
A workaround to this issue is to not pass arbitrary user input to the
rendermethod. Instead, verify that data before passing it to therendermethod.For example, change this:
To this:
Patches
To aid users who aren't able to upgrade immediately we have provided patches for it. It is in git-am format and consist of a single changeset.
Credits
Thanks to both Jyoti Singh and Tobias Kraze from makandra for reporting this and working with us in the patch!
References