How severe is CVE-2026-69213?

CVE-2026-69213 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-69213?

CVE-2026-69213 affects the following packages: org.http4s:http4s-ember-core_2.12 (Maven), org.http4s:http4s-ember-core_2.13 (Maven), org.http4s:http4s-ember-core_3 (Maven), org.http4s:http4s-ember-core_3 (Maven), org.http4s:http4s-ember-core_2.13 (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-69213?

Update org.http4s:http4s-ember-core_2.12 to 0.23.35 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-69213 is resolved across your whole dependency graph.

How do I detect CVE-2026-69213 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.http4s:http4s-ember-core_2.12, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-69213 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-69213 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-69213 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-69213?

CVE-2026-69213 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 50th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-69213?

CVE-2026-69213 is classified as Uncontrolled Resource Consumption (CWE-400), CWE-770 (CWE-770). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-69213 published, and has it been updated?

CVE-2026-69213 was published on September 15, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

HIGH severity

CVE-2026-69213 — http4s-ember-core_2.12

HIGHFix: http4s/http4s@13fe24d

CVE-2026-69213 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in org.http4s:http4s-ember-core_2.12. A fix is available for org.http4s:http4s-ember-core_2.12 — see the affected versions and patch details below.

Http4s Ember HTTP/2: unbounded outbound frame queue

Also known asGHSA-8f3q-3jmv-7prw

Published

Sep 15, 2026

Updated

Oct 28, 2026

Affected

5 pkgs

Patched

5 / 5

Exploits

None indexed

Exploitation data as of Oct 29, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-69213.

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs50th percentile — riskier than 50% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-69213 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 398,142 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

5 pkgs affected

☕org.http4s:http4s-ember-core_2.12☕org.http4s:http4s-ember-core_2.13☕org.http4s:http4s-ember-core_3☕org.http4s:http4s-ember-core_3☕org.http4s:http4s-ember-core_2.13

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Ember's HTTP/2 connection serializes all outgoing frames through a single unbounded queue drained by one writer fiber (writeLoop). When the write side stalls, any frames the connection keeps producing accumulate in that queue without limit. The peer can drive this cheaply because the connection emits a control frame in response to inbound frames it does not flow-control: one PING ACK per PING, one SETTINGS ACK per SETTINGS, and a WINDOW_UPDATE per inbound DATA. A single unauthenticated connection can therefore exhaust heap and OOM the process.

This affects an ember server (malicious client) and an ember client (malicious/compromised server that floods the client and stops reading its ACKs).

Impact

Unauthenticated remote denial of service (OOM) against any ember server built .withHttp2, from a single connection, at negligible attacker cost (tiny control frames). Also affects an ember client talking to a hostile HTTP/2 server.

Preconditions

Ember server or client built .withHttp2, speaking to a hostile or compromised peer.

Workarounds

Disable HTTP/2 (do not call .withHttp2).

Affected Packages

5 total 5 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.http4s:http4s-ember-core_2.12`	all versions	0.23.35`org.http4s:http4s-ember-core_2.12:0.23.35`
☕Maven	`org.http4s:http4s-ember-core_2.13`	all versions	0.23.35`org.http4s:http4s-ember-core_2.13:0.23.35`
☕Maven	`org.http4s:http4s-ember-core_3`	all versions	0.23.35`org.http4s:http4s-ember-core_3:0.23.35`
☕Maven	`org.http4s:http4s-ember-core_3`	≥ 1.0.0-M1&&< 1.0.0-M47	1.0.0-M47`org.http4s:http4s-ember-core_3:1.0.0-M47`
☕Maven	`org.http4s:http4s-ember-core_2.13`	≥ 1.0.0-M1&&< 1.0.0-M47	1.0.0-M47`org.http4s:http4s-ember-core_2.13:1.0.0-M47`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.http4s:http4s-ember-core_2.12, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.http4s:http4s-ember-core_2.12 to 0.23.35 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-69213 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

Ember's HTTP/2 connection serializes all outgoing frames through a single unbounded queue drained by one writer fiber (`writeLoop`). When the write side stalls, any frames the connection keeps producing accumulate in that queue without limit. The peer can drive this cheaply because the connection emits a control frame in response to inbound frames it does not flow-control: one `PING` ACK per `PING`, one `SETTINGS` ACK per `SETTINGS`, and a `WINDOW_UPDATE` per inbound DATA. A single unauthenticated connection can therefore exhaust heap and OOM the process. This affects an ember server (mali