CVE-2026-66357: inets,httpd:HTTP Request Smuggling via obs-fold Header Continuation
httpd has never implemented obs-fold (RFC 2616 §2.2 / RFC 7230 §3.2.4 header continuation lines). Every CRLF followed by a non-CRLF octet unconditionally starts a new header. This missing feature became a security concern as the understanding of HTTP request smuggling attacks evolved.
This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown.
Affected Software
Event History
Frequently Asked Questions
Which deployments are known to be affected?
Known affected releases are OTP 17.0 through before 27.3.4.17, OTP 28.0 through before 28.5.0.6, and OTP 29.0 through before 29.0.6. The corresponding affected inets ranges are 5.10 through before 9.3.2.7, 9.4 through before 9.6.2.3, and 9.7 through before 9.7.2.2.
Are releases older than OTP 17.0 affected?
It is unknown whether OTP releases before 17.0, corresponding to inets releases before 5.10, are affected.
What fixed versions are available?
Upgrade to OTP 27.3.4.17, 28.5.0.6, or 29.0.6, as applicable. The corresponding fixed inets versions are 9.3.2.7, 9.6.2.3, and 9.7.2.2.