Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [day] [month] [year] [list]
Date: Wed, 13 Mar 2019 10:14:54 -0700
From: Aaron Patterson <>
Subject: [CVE-2019-5420] Possible Remote Code Execution Exploit in Rails
 Development Mode

There is a possible a possible remote code executing exploit in Rails when in
development mode. This vulnerability has been assigned the CVE identifier

Versions Affected:  6.0.0.X, 5.2.X.
Not affected:       None.
Fixed Versions:     6.0.0.beta3,

With some knowledge of a target application it is possible for an attacker to
guess the automatically generated development mode secret token.  This secret
token can be used in combination with other Rails internals to escalate to a
remote code execution exploit.

All users running an affected release should either upgrade or use one of the
workarounds immediately.

The 6.0.0.beta3 and releases are available at the normal locations.

This issue can be mitigated by specifying a secret key in development mode.
In "config/environments/development.rb" add this:

  config.secret_key_base = SecureRandom.hex(64)

To aid users who aren't able to upgrade immediately we have provided patches for
the two supported release series. They are in git-am format and consist of a
single changeset.

* 6-0-railties-dev-mode-token.patch - Patch for 6.0 series
* 5-2-railties-dev-mode-token.patch - Patch for 5.2 series

Please note that only the 5.2.x, 5.1.x, 5.0.x, and 4.2.x series are supported
at present. Users of earlier unsupported releases are advised to upgrade as
soon as possible as we cannot guarantee the continued availability of security
fixes for unsupported releases.

Thanks to ooooooo_q

Aaron Patterson

View attachment "5-2-railties-dev-mode-token.patch" of type "text/plain" (5512 bytes)

View attachment "6-0-railties-dev-mode-token.patch" of type "text/plain" (5566 bytes)

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)

Powered by blists - more mailing lists

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.