Description
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, an unauthenticated HTTP/2 peer can cause an out-of-memory denial of service in the Ember backend with HTTP/2 enabled. The Hpack wrapper in ember-core/shared/src/main/scala/org/http4s/ember/core/h2/Hpack.scala concatenates HEADERS and CONTINUATION frame fragments and decodes them into a single List, but maxHeaderSize accounting does not include indexed headers or HPACK per-header overhead. A small compressed header block can therefore expand into a much larger decoded representation that remains in memory for processing. Servers exposed to untrusted HTTP/2 traffic and clients directed to an untrusted HTTP/2 server are affected, and concurrent malicious connections can exhaust the process heap. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
http4s http4s
< 0.23.35affected>= 1.0.0-M1, < 1.0.0-M46affected
org.http4s http4s-ember-core_2.12
< 0.23.35affected
org.http4s http4s-ember-core_2.13
>= 1.0.0-M1, < 1.0.0-M46affected< 0.23.35affected
org.http4s http4s-ember-core_3
>= 1.0.0-M1, < 1.0.0-M46affected< 0.23.35affected