Published 11 months ago
Category: Code Injection
Severity: Critical

Vulnerability in railties

There is a possible a possible remote code executing exploit in Rails when in development mode. This vulnerability has been assigned the CVE identifier CVE-2019-5420.

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)


Thanks to ooooooo_q

CVSS Metrics
Access Vector Access Complexity Authentication Confidentiality Impact Integrity Impact Availability Impact
n/a n/a n/a n/a n/a n/a
Patched Versions

~> 5.2.2 >= >= 6.0.0.beta3

Unaffected Versions

< 5.2.0