CVE-2026-88975 json
Http4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE
published 2026-09-15 54 d ago modified 2026-09-16 53 d ago also GHSA-gq9p-f254-h286 , EUVD-2026-79239
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.6%
- EPSS 0.6% chance of exploitation in 30 days, percentile 50%
- public exploits
- 0
- none known
Summary
Http4s is a Scala interface for HTTP services. Prior to 0.23.37 and 1.0.0-M48, Ember’s HTTP/2 read loop parses a frame’s 24-bit declared length but waits to buffer the entire payload before comparing it with SETTINGS_MAX_FRAME_SIZE. An unauthenticated peer can declare a payload near 16 MiB on a connection where Ember advertised 16 KiB and either complete or slowly stream it, causing up to 1024-fold memory amplification per connection before processFrame can reject the frame. The shared H2Connection.readLoop affects withHttp2 servers and clients, while HTTP/2-disabled configurations are unaffected, and the patch rejects oversized frames before buffering their payloads. This issue is fixed in versions 0.23.37 and 1.0.0-M48.
Patch / fix
- maven org.http4s:http4s-ember-core_2.13 0.23.37, 1.0.0-M48
- maven org.http4s:http4s-ember-core_2.12 0.23.37
- maven org.http4s:http4s-ember-core_3 0.23.37, 1.0.0-M48
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 53 d ago
Exploit prediction
0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| GitHub | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| maven | org.http4s:http4s-ember-core_2.13 | <0.23.37 >=1.0.0-M1, <1.0.0-M48 |
0.23.37 1.0.0-M48 |
| maven | org.http4s:http4s-ember-core_2.12 | <0.23.37 |
0.23.37 |
| maven | org.http4s:http4s-ember-core_3 | <0.23.37 >=1.0.0-M1, <1.0.0-M48 |
0.23.37 1.0.0-M48 |
Affected products
- http4s http4s
Classification
- Weakness
-
- CWE-400 Uncontrolled Resource Consumption
References
Sources
- CVE List CVE-2026-88975
- GitHub Advisory GHSA-gq9p-f254-h286
- NVD CVE-2026-88975
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.