CVE-2020-5247
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | bookworm | fixed | 3.12.4-1 |
| debian | bullseye | fixed | 3.12.4-1 |
| debian | forky | fixed | 3.12.4-1 |
| debian | sid | fixed | 3.12.4-1 |
| debian | trixie | fixed | 3.12.4-1 |
References
- https://github.com/puma/puma/security/advisories/GHSA-84j7-475p-hp8v
- https://www.suse.com/security/cve/CVE-2020-5247.html
- https://nvd.nist.gov/vuln/detail/CVE-2020-5247
- https://github.com/puma/puma/commit/c36491756f68a9d6a8b3a49e7e5eb07fe6f1332f
- https://github.com/puma/puma
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/puma/CVE-2020-5247.yml
- https://lists.debian.org/debian-lts-announce/2022/05/msg00034.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/BMJ3CGZ3DLBJ5WUUKMI5ZFXFJQMXJZIK
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DIHVO3CQMU7BZC7FCTSRJ33YDNS3GFPK
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/NJ3LL5F5QADB6LM46GXZETREAKZMQNRD
- https://owasp.org/www-community/attacks/HTTP_Response_Splitting
- https://www.ruby-lang.org/en/news/2019/10/01/http-response-splitting-in-webrick-cve-2019-16254
- https://security-tracker.debian.org/tracker/CVE-2020-5247
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.