Resource exhaustion in Http4s
CVE-2026-69202
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/2 flow-control window is replenished according to bytes received from the network rather than bytes consumed by the application, while each stream stores DATA in an unbounded channel. A hostile peer can therefore send a body faster than a slow or non-draining application consumes it, retaining payloads in heap on an ember-server or ember-client configured with withHttp2. The patch bounds the per-stream H2Connection body channel so application consumption applies backpressure. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Vulnerability class: DoS (Denial of Service)
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Http4s — versions < 0.23.35, >= 1.0.0-M1, < 1.0.0-M47
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-69202?
- CVE-2026-69202 is a high-severity vulnerability in Http4s, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-09-15.
- How severe is CVE-2026-69202?
- High severity. CVSS v3 base score is 7.5 out of 10.