CVE-2019-5420
CriticalPublic exploitUse of Insufficiently Random Values in Railties Allows Remote Code Execution
Published Mar 13, 2019 · Updated Sep 9, 2026 · Also known as DEBIAN-CVE-2019-5420, GHSA-m42h-mh85-4qgc
Key Facts
Patch immediately- CVE-2019-5420 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Rails (Rubyonrails), Debian Linux, Fedora (Fedoraproject) and 5 more products.
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 89% probability of exploitation in the next 30 days.
- Fixed versions are available, including Rails 2:5.2.2.1+dfsg-1, Rails 5.2.2.1, railties 5.2.2.1.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
89%
Higher than 99.7% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2019-5420 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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.
Affected Products
47 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| RailsRubyonrails | 6.0.0-beta1, 6.0.0-beta2 | 5.2.2.1 |
| Debian LinuxDebian | 8.0 | n/a |
| FedoraFedoraproject | 30 | n/a |
| railtiesrubygems | >= 5.2.0 | 5.2.2.1 |
| rmt-server-configsuse | See advisory | 2.6.5-lp151.2.18.2 |
Patched Releases
Rails
2:5.2.2.1+dfsg-1, 5.2.2.1
railties
5.2.2.1
rmt-server
2.6.13-1.1, 2.6.5-3.18.1, 2.6.5-3.3.1, 2.6.5-3.34.1, 2.6.5-lp151.2.18.2, 2.6.5-lp152.2.3.1
rmt-server-config
2.6.13-1.1, 2.6.5-3.18.1, 2.6.5-3.3.1, 2.6.5-3.34.1, 2.6.5-lp151.2.18.2, 2.6.5-lp152.2.3.1
rmt-server-pubcloud
2.6.13-1.1, 2.6.5-lp151.2.18.2, 2.6.5-lp152.2.3.1
Timeline
Publicly disclosed
Mar 13, 2019
Last updated
Sep 9, 2026
Weakness Type
- CWE-77 Improper Neutralization of Special Elements used in a Command ('Command Injection')
- CWE-330 Use of Insufficiently Random Values
- CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
References
- advisoryhttps://bugzilla.suse.com/1165548
- advisoryhttps://bugzilla.suse.com/1168554
- advisoryhttps://bugzilla.suse.com/1172177
- advisoryhttps://bugzilla.suse.com/1172182
- advisoryhttps://bugzilla.suse.com/1172184
FAQ
Common Questions.
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.
Affected: Rails (Rubyonrails) versions 6.0.0-beta1, 6.0.0-beta2; Debian Linux versions 8.0; Fedora (Fedoraproject) versions 30, among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Rails 2:5.2.2.1+dfsg-1, Rails 5.2.2.1, railties 5.2.2.1.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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