CVE-2026-66357
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.
Scoring
- Severity
- HIGH
- CVSS base score
- 8.3
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:L/SA:N
- EPSS probability
- 0.33%
- CWE
- CWE-444
- Published
- 2026-09-01
- Last modified
- 2026-09-08
Affected products
- Erlang OTP
- Erlang OTP
- Erlang OTP
- Erlang OTP
- Erlang OTP
- Erlang OTP
- Erlang OTP
- Erlang OTP
Weakness type
Related vulnerabilities
- CVE-2026-81356 — Visual Studio Code Security Feature Bypass Vulnerability
- CVE-2026-19203 — A client may issue specially crafted HTTP/1.1 chunked requests to a Jetty server that cause Jetty...
- CVE-2026-18540 — undici vulnerable to downstream response splitting via retry interceptor
- CVE-2026-84380 — HTTPX2: Conflicting Content-Length and Transfer-Encoding headers can be auto-generated
- CVE-2026-84363 — Hono: Query parser reads parameters after the URL fragment, causing cache-key and proxy interpretation differentials
- CVE-2026-78605 — Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') in Elasticsearch Leading to Information Disclosure
- CVE-2026-73812 — inets, httpd: HTTP Request Smuggling via Transfer-Encoding and Content-Length
- CVE-2026-73276 — inets, httpd: HTTP Request Smuggling via Whitespace-Before-Colon Header Dropping i