CVE-2019-16254

What it is

Ruby through 2.4.7, 2.5.x through 2.5.6, and 2.6.x through 2.6.4 allows HTTP Response Splitting. If a program using WEBrick inserts untrusted input into the response header, an attacker can exploit it to insert a newline character to split a header, and inject malicious content to deceive clients. NOTE: this issue exists because of an incomplete fix for CVE-2017-17742, which addressed the CRLF vector, but did not address an isolated CR or an isolated LF.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

4.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2019-11-26 18:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 02:22 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 4.6% in the next 30 days (EPSS).
• Severity: 5.3 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2019-11-26 18:15 UTC

Last modified

2026-06-17 02:22 UTC

Exploit probability

4.6% · EPSS, next 30 days

Weakness

CWE-74

Record status

Modified

Affected

• ruby-lang Ruby ≤ 2.3.0
• ruby-lang Ruby ≤ 2.4.7
• ruby-lang Ruby ≤ 2.5.6
• ruby-lang Ruby ≤ 2.6.4
• Debian Linux 8.0

Attack profile CVSS 3.1 · 5.3

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2019-16254.md and follow it. Check whether this project is affected by CVE-2019-16254. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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