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CVE-2019-5418

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in Rails Ruby on Rails. For every flaw being used in attacks, see Exploited flaws; for Rails’s, see Rails flaws being used in attacks.

CVE-2019-5418 is a security flaw in Rails Ruby on Rails. Attackers can read files on Rails Ruby on Rails that should be out of reach. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 7 Jul 2025.[1]

Rails Ruby on Rails is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Rails has published a fix or advice.

Description

CISA calls it a path traversal in Rails Ruby on Rails. In its words: “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.”[1]

The underlying weakness is path traversal (CWE-22), in MITRE’s list of common software weaknesses.[2]

It scores 7.5 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]

Affected versions

NVD’s record doesn’t list version ranges for it; Rails’s advisory has them[3]. CISA names the product as Rails Ruby on Rails.

Most families won’t have Rails Ruby on Rails; it’s for whoever looks after IT at work.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 7 Jul 2025, 2,294 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 28 Jul 2025 to fix it.[1]

FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 99%. That’s in the top 1% of the flaws it scores.[4]

CISA assesses it as automatable: attackers can run it against many targets at once.

CISA doesn’t say who was attacked, or how.

Fix

Rails has published a fix or advice.[3] CISA’s 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.”[1]

  1. Check whether you use it.Rails Ruby on Rails is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
  2. Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 28 Jul 2025 to fix it.
  3. If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.

You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.

Timeline

DateEvent
The flaw is made public in the National Vulnerability Database, with a severity score of 7.5.[2]
CISA adds it to its catalog of flaws known to be used in attacks.[1]
CISA’s deadline for US government agencies to fix it.[1]
FIRST puts the odds of it being used in attacks in the next 30 days at 99%.[4]

See also

Other Rails Ruby on Rails flaws

Other path traversal flaws

  • CVE-2025-61624, Fortinet products: path traversal ·
  • CVE-2021-3199, ONLYOFFICE Docs: server path traversal ·
  • CVE-2026-104286, Fortinet FortiMail: path traversal ·
  • CVE-2026-93616, Check Point products: path traversal ·
  • CVE-2026-66384, JFrog Artifactory: improper limitation of a pathname to a restricted directory ·

Added the same day

  • CVE-2019-9621, Synacor Zimbra Collaboration Suite (ZCS): server-side request forgery (SSRF) ·
  • CVE-2016-10033, PHPMailer: command injection ·
  • CVE-2014-3931, Looking Glass Multi-Router Looking Glass (MRLG): buffer overflow ·

Every Rails flaw on CISA’s list · Everything added in July 2025

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “Rails Ruby on Rails Path Traversal Vulnerability”. Known Exploited Vulnerabilities Catalog, added 7 Jul 2025.
  2. ^ National Institute of Standards and Technology. “CVE-2019-5418 Detail”. National Vulnerability Database, published 27 Mar 2019.
  3. ^ Rails. Advisories and fixes: web.archive.org.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.985, percentile 99.9, 31 Oct 2026.
  5. CVE Program. “CVE-2019-5418”. The official CVE record.

This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.