🛡️ CVE-2020-5247 — ruby

🟠 CVSS 8.0 — High ✅ No Known Exploit OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

HTTP Response Splitting in Puma

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.

Affected software

CVE-2020-5247 is recorded against 2 packages.

  • ruby
  • ruby-min

Timeline and source

Published on 6 March 2024 and last revised on 6 November 2025. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
lists.debian.org (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
owasp.org (Web)
www.ruby-lang.org (Web)
nvd.nist.gov (Web)

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector N/A
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2024-03-06
Updated 2026-08-12
Modified 2025-11-06
Fix URL N/A

Affected Packages

Software From version Fixed in
ruby — —
ruby-min — —

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