CVE-2026-66357 PUBLISHED

inets,httpd:HTTP Request Smuggling via obs-fold Header Continuation

Assigner: EEF
Reserved: 17.08.2026 Published: 01.09.2026 Updated: 01.09.2026

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.

Metrics

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
CVSS Score: 8.3

Product Status

Vendor Erlang
Product OTP
Versions Default: unaffected
  • unknown from 0 to 17.0 (excl.)
  • affected from 17.0 to 27.3.4.17 (excl.)
  • affected from 28.0 to 28.5.0.6 (excl.)
  • affected from 29.0 to 29.0.6 (excl.)
Vendor Erlang
Product OTP
Versions Default: unaffected
  • unknown from 0 to 5.10 (excl.)
  • affected from 5.10 to 9.3.2.7 (excl.)
  • affected from 9.4 to 9.6.2.3 (excl.)
  • affected from 9.7 to 9.7.2 (excl.)
Vendor Erlang
Product OTP
Versions Default: unaffected
  • affected from 84adefa331c4159d432d22840663c38f155cd4c1 to * (excl.)

Credits

  • Lukas Backström / Erlang Solutions finder
  • Konrad Pietrzak / Ericsson remediation developer

References

Problem Types

  • CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') CWE

Impacts

  • CAPEC-33 HTTP Request Smuggling