An issue was discovered in Ruby through 2.5.8, 2.6.x through 2.6.6, and 2.7.x through 2.7.1. WEBrick, a simple HTTP server bundled with Ruby, had not checked the transfer-encoding header value rigorously. An attacker may potentially exploit this issue to bypass a reverse proxy (which also has a poor header check), which may lead to an HTTP Request Smuggling attack.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-25613
• ruby/webrick@8946bb3
• https://hackerone.com/reports/965267
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PFP3E7KXXT3H3KA6CBZPUOGA5VPFARRJ/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/YTZURYROG3FFED3TYCQOBV66BS4K6WOV/
• https://security.netapp.com/advisory/ntap-20210115-0008/
• https://www.ruby-lang.org/en/news/2020/09/29/http-request-smuggling-cve-2020-25613/
• ruby/webrick@076ac63
• https://github.com/rubysec/ruby-advisory-db/blob/master/gems/webrick/CVE-2020-25613.yml
• https://lists.debian.org/debian-lts-announce/2023/04/msg00033.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PFP3E7KXXT3H3KA6CBZPUOGA5VPFARRJ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YTZURYROG3FFED3TYCQOBV66BS4K6WOV/
• https://security.gentoo.org/glsa/202401-27