Vulnerability details
CVE-2026-69213
http4s http4s
Http4s Ember HTTP/2: unbounded outbound frame queue
CVSS 3.1
7.5High
Official description
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.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 7.5High | 3.1 | CVEProject cvelistV5 (CNA) (GitHub_M) | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| http4s | http4s | < 0.23.35 | CVEProject cvelistV5 (CNA) |
| http4s | http4s | >= 1.0.0-M1, < 1.0.0-M47 | CVEProject cvelistV5 (CNA) |
References and advisories
4- https://github.com/http4s/http4s/security/advisories/GHSA-8f3q-3jmv-7prw x_refsource_CONFIRM
- https://github.com/http4s/http4s/commit/13fe24d6440bde2f1eb70121486cf59c278e6bae x_refsource_MISC
- https://github.com/http4s/http4s/releases/tag/v0.23.35 x_refsource_MISC
- https://github.com/http4s/http4s/releases/tag/v1.0.0-M47 x_refsource_MISC
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Details
- Published
- 2026-09-15
- Last updated
- 2026-09-17
- State
- Published
- Assigner (CNA)
- GitHub_M
Exploit prediction (EPSS)
0.63%
Probability of exploitation in 30 days
50.4%
Percentile (among all CVEs)
SSVC assessment (CISA)
- Automatable
- Yes
- Exploitation
- None
- Technical impact
- Partial
Weaknesses (CWE)
- CWE-400Uncontrolled Resource Consumption
- CWE-770Allocation of Resources Without Limits or Throttling