CVE-2020-5247
HTTP Response Splitting in Puma
Description
In Puma (RubyGem) before 4.3.2 and before 3.12.3, if an application using Puma allows untrusted input in a response header, an attacker can use newline characters (i.e. `CR`, `LF` or`/r`, `/n`) to end the header and inject malicious content, such as additional headers or an entirely new response body. This vulnerability is known as HTTP Response Splitting. While not an attack in itself, response splitting is a vector for several other attacks, such as cross-site scripting (XSS). This is related to CVE-2019-16254, which fixed this vulnerability for the WEBrick Ruby web server. This has been fixed in versions 4.3.2 and 3.12.3 by checking all headers for line endings and rejecting headers with those characters.
How to fix CVE-2020-5247
To remediate CVE-2020-5247, upgrade the affected package to a fixed version below.
- —upgrade to 2.3.1 or later
- —upgrade to 2.3.1 or later
- —upgrade to 3.12.4-1 or later
- —upgrade to 3.12.4 or later
Is CVE-2020-5247 being exploited?
Low — EPSS is 2.1%, meaning exploitation activity has not been observed at scale.
Affected packages (4)
- from 0, < 2.3.1, >= 2.4.0, < 2.4.8, >= 2.5.0, < 2.5.7, >= 2.6.0, < 2.6.5
- from 0, < 2.3.1, >= 2.4.0, < 2.4.8, >= 2.5.0, < 2.5.7, >= 2.6.0, < 2.6.5
- from 0, < 3.12.4-1
- from 0, < 3.12.4
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L |