TI-2026-48557 Aliases CVE-2026-69213 GHSA-8f3q-3jmv-7prw

Http4s Ember HTTP/2: unbounded outbound frame queue

MEDIUM 40CWE-400Published 2026-09-15 · Updated 2026-09-17

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-400.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.0063 50th percentileScored 2026-11-07

Fix Fixed http4s (http4s): 0.23.35, 1.0.0-M47org.http4s:http4s-ember-core_2.12 (Maven): 0.23.35+2 more products

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
http4s	http4s	before 0.23.35; 1.0.0-M1 to before 1.0.0-M47	0.23.35, 1.0.0-M47	Patch available	CNA
—	org.http4s:http4s-ember-core_2.12 (Maven)	before 0.23.35	0.23.35	Patch available	GHSA-8f3q-3jmv-7prw
—	org.http4s:http4s-ember-core_2.13 (Maven)	before 0.23.35	0.23.35	Patch available	GHSA-8f3q-3jmv-7prw
—	org.http4s:http4s-ember-core_3 (Maven)	before 0.23.35	0.23.35	Patch available	GHSA-8f3q-3jmv-7prw
—	org.http4s:http4s-ember-core_3 (Maven)	1.0.0-M1 to before 1.0.0-M47	1.0.0-M47	Patch available	GHSA-8f3q-3jmv-7prw
—	org.http4s:http4s-ember-core_2.13 (Maven)	1.0.0-M1 to before 1.0.0-M47	1.0.0-M47	Patch available	GHSA-8f3q-3jmv-7prw

http4s Vendorhttp4s Affected before 0.23.35; 1.0.0-M1 to before 1.0.0-M47 Fixed in 0.23.35, 1.0.0-M47 Patch available CNA
org.http4s:http4s-ember-core_2.12 (Maven) Vendor— Affected before 0.23.35 Fixed in 0.23.35 Patch available GHSA-8f3q-3jmv-7prw
org.http4s:http4s-ember-core_2.13 (Maven) Vendor— Affected before 0.23.35 Fixed in 0.23.35 Patch available GHSA-8f3q-3jmv-7prw
org.http4s:http4s-ember-core_3 (Maven) Vendor— Affected before 0.23.35 Fixed in 0.23.35 Patch available GHSA-8f3q-3jmv-7prw
org.http4s:http4s-ember-core_3 (Maven) Vendor— Affected 1.0.0-M1 to before 1.0.0-M47 Fixed in 1.0.0-M47 Patch available GHSA-8f3q-3jmv-7prw
org.http4s:http4s-ember-core_2.13 (Maven) Vendor— Affected 1.0.0-M1 to before 1.0.0-M47 Fixed in 1.0.0-M47 Patch available GHSA-8f3q-3jmv-7prw

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:typelevel:http4s::::::::	—	—	http4s

cpe:2.3:a:typelevel:http4s:*:*:*:*:*:*:*:* Versions — — ·http4s

Remediation

Fix · CNA http4s (http4s) Fixed in 0.23.35, 1.0.0-M47
Fix · GHSA-8f3q-3jmv-7prw org.http4s:http4s-ember-core_2.12 (Maven) Fixed in 0.23.35 Advisory →
Fix · GHSA-8f3q-3jmv-7prw org.http4s:http4s-ember-core_2.13 (Maven) Fixed in 0.23.35 Advisory →
Fix · GHSA-8f3q-3jmv-7prw org.http4s:http4s-ember-core_3 (Maven) Fixed in 0.23.35 Advisory →
Fix · GHSA-8f3q-3jmv-7prw org.http4s:http4s-ember-core_3 (Maven) Fixed in 1.0.0-M47 Advisory →
Fix · GHSA-8f3q-3jmv-7prw org.http4s:http4s-ember-core_2.13 (Maven) Fixed in 1.0.0-M47 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-69213
2026-10-03 Alias added: GHSA-8f3q-3jmv-7prw
2026-10-28 EPSS moved to the 50th–90th percentile

References

Other 5

TI-2022-13223 mTLS client verification is skipped in fs2 on Node.js CVSS 3.1CRITICAL 9.8
TI-2023-08714 Http4s has fatal error parsing User-Agent and Server headers CVSS 3.1HIGH 7.5
TI-2022-06031 Hash collision in typelevel jawn CVSS 3.1HIGH 7.5
TI-2025-37261 Http4s vulnerable to HTTP Request Smuggling due to improper handling of HTTP trailer section CVSS 4.0MEDIUM 6.3
TI-2026-44185 http4s-scala-xml has an XML External Entity (XXE) processing issue CVSS 3.1CRITICAL 9.3
TI-2020-04336 Local file inclusion vulnerability in http4s CVSS 3.1HIGH 7.6

See all 36 →

Sources

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