CVE-2026-69203
Http4s Ember HTTP/2: does not enforce SETTINGS_MAX_CONCURRENT_STREAMS
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, An Ember server with HTTP/2 enabled through withHttp2 does not enforce SETTINGS_MAX_CONCURRENT_STREAMS for peer-created streams. One unauthenticated connection can open an unbounded number of streams, each retaining per-stream state until heap exhaustion. The same unchecked allocation is reachable in an ember-client through server-initiated PUSH_PROMISE frames because enablePush is not enforced. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Deferred | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.63% · top 50% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Mavenorg.http4s:http4s-ember-core_2.12GHSA-9vwc-pc8p-253q (opens in a new tab)
- Mavenorg.http4s:http4s-ember-core_2.13GHSA-9vwc-pc8p-253q (opens in a new tab)
- Mavenorg.http4s:http4s-ember-core_3GHSA-9vwc-pc8p-253q (opens in a new tab)
References (4)
- https://github.com/http4s/http4s/security/advisories/GHSA-9vwc-pc8p-253q (opens in a new tab)x_refsource_CONFIRM
- https://github.com/http4s/http4s/commit/4983de1f93f2caaa3b9de310cf6a9db32c50d66e (opens in a new tab)x_refsource_MISC
- https://github.com/http4s/http4s/releases/tag/v0.23.35 (opens in a new tab)x_refsource_MISC
- https://github.com/http4s/http4s/releases/tag/v1.0.0-M47 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-9vwc-pc8p-253q (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-69203)Record last updated .