← CVE Intelligence

CVE-2026-69213

Http4s Ember HTTP/2: unbounded outbound frame queue PUBLISHED

Description (CNA)

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember HTTP/2 serializes outbound frames through one unbounded queue consumed by writeLoop. When the peer stops reading, an unauthenticated HTTP/2 client can continue sending PING, SETTINGS, or DATA frames that cause Ember to enqueue acknowledgments or WINDOW_UPDATE frames faster than the writer drains them, exhausting heap memory on a server built with withHttp2. The shared behavior also affects an ember-client connected to a hostile HTTP/2 server, and the patch replaces the unbounded path with bounded, backpressured outbound queues. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

Affected (CNA)

Vendor / productVersions
http4s / http4saffected < 0.23.35; affected >= 1.0.0-M1, < 1.0.0-M47

CWE

CWE-400, CWE-770

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.