CVE-2019-5420
A remote code execution vulnerability in development mode Rails <5.2.2.1, <6.0.0.beta3 can allow an attacker to guess the automatically generated development mode secret token.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 89.3%, higher than 100% of all known CVEs. Patch or mitigate before the next change window.
Description
A remote code execution vulnerability in development mode Rails <5.2.2.1, <6.0.0.beta3 can allow 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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 89.33% probability · 100th percentile
- Public exploits
- 1 in Exploit-DB · verified · first 2 May 2019
- CISA KEV
- Not listed
- Weakness
- CWE-77, CWE-330
- Affected
- rubyonrails/rails · debian/debian linux · fedoraproject/fedora
- Source
- support@hackerone.com
EPSS moved from 89.7% on 24 September 2026 to 89.3% on 3 November 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- http://packetstormsecurity.com/files/152704/Ruby-On-Rails-DoubleTap-Development-Mode-secret_key_base-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
- https://groups.google.com/forum/#%21topic/rubyonrails-security/IsQKvDqZdKw
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y43636TH4D6T46IC6N2RQVJTRFJAAYGA/
- https://weblog.rubyonrails.org/2019/3/13/Rails-4-2-5-1-5-1-6-2-have-been-released/Patch, Vendor Advisory
- https://www.exploit-db.com/exploits/46785/Exploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/152704/Ruby-On-Rails-DoubleTap-Development-Mode-secret_key_base-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
- https://groups.google.com/forum/#%21topic/rubyonrails-security/IsQKvDqZdKw
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y43636TH4D6T46IC6N2RQVJTRFJAAYGA/
- https://weblog.rubyonrails.org/2019/3/13/Rails-4-2-5-1-5-1-6-2-have-been-released/Patch, Vendor Advisory
- https://www.exploit-db.com/exploits/46785/Exploit, Third Party Advisory, VDB Entry
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.