CVE-2019-5418: Rails Ruby on Rails

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

Yes, if you run Rails Ruby on Rails. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2025-07-07, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2025-07-28; treat that as the outer limit, not the target.
EPSS 98.5%, percentile 99.9: FIRST’s model estimates a 98.5% chance of exploitation activity in the next 30 days, higher than 99.9% of all scored CVEs (very high). EPSS is a probability, not a verdict.
Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

What it is

There is a File Content Disclosure vulnerability in Action View

CISA’s summary

Rails Ruby on Rails contains a path traversal vulnerability in Action View. Specially crafted accept headers in combination with calls to `render file:` can cause arbitrary files on the target server to be rendered, disclosing the file contents.

Weakness type: CWE-22.

Product: Rails Ruby on Rails · Assigned by: hackerone · Published: 2019-03-27

Affected and fixed versions

Vendor	Product	Affected versions (per CVE record)
Rails	https://github.com/rails/rails	5.2.2.1, 5.1.6.2, 5.0.7.2, 4.2.11.1

Severity scores

Scored by	CVSS	Score	Vector
CISA-ADP	3.1	7.5 High	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`

Attack vector: network (remotely reachable)
Attack complexity: low
Privileges required: none (no login)
User interaction: none
Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

CISA KEV: added 2025-07-07; federal due date 2025-07-28. Known ransomware use: Unknown.
CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA SSVC assessment: exploitation active, automatable yes, technical impact partial.
FIRST EPSS (model of 2026-10-21): 98.51% probability of exploitation activity in the next 30 days; percentile 99.9.

Timeline

2019-03-27 — CVE record published by hackerone
2025-07-07 — Added to CISA’s Known Exploited Vulnerabilities catalog
2025-07-28 — CISA remediation deadline for US federal agencies
2025-10-21 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Should you act?

What it is

CISA’s summary

Affected and fixed versions

Severity scores

Exploitation and urgency

Timeline

Sources and references

Vendor and project advisories, patches

Vulnerability records

Government

Other references from the CVE record and advisory