CVE-2026-69205 json
Http4s: Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling)
published 2026-09-15 54 d ago modified 2026-09-16 53 d ago also GHSA-9998-894r-fwvr , EUVD-2026-79190
- cvss
- 8.7
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 41%
- public exploits
- 0
- none known
Summary
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HeaderP.parse uses a case-sensitive substring test for the Transfer-Encoding value and decodes header bytes with the platform default charset. Values such as Chunked are not recognized, values such as notchunked are incorrectly accepted, and Unicode case folding can turn a Kelvin-sign byte sequence into a match when UTF-8 is used. Intermediaries that apply RFC-compliant token and charset rules can therefore disagree with Ember’s Content-Length or zero-length framing, enabling TE.CL or TE.0 request smuggling, access-control bypass, cross-user request hijacking, and cache poisoning on the server path. Response smuggling through an ember-client gateway requires a malicious or compromised upstream. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Patch / fix
- maven org.http4s:http4s-ember-core_3 0.23.35, 1.0.0-M47
- maven org.http4s:http4s-ember-core_2.13 0.23.35, 1.0.0-M47
- maven org.http4s:http4s-ember-core_2.12 0.23.35
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 54 d ago
Exploit prediction
0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N |
| GitHub | 3.1 | 8.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| maven | org.http4s:http4s-ember-core_3 | <0.23.35 >=1.0.0-M1, <1.0.0-M47 |
0.23.35 1.0.0-M47 |
| maven | org.http4s:http4s-ember-core_2.13 | <0.23.35 >=1.0.0-M1, <1.0.0-M47 |
0.23.35 1.0.0-M47 |
| maven | org.http4s:http4s-ember-core_2.12 | <0.23.35 |
0.23.35 |
Affected products
- http4s http4s
Classification
- Weakness
-
- CWE-444 Inconsistent Interpretation of HTTP Requests
References
Sources
- CVE List CVE-2026-69205
- GitHub Advisory GHSA-9998-894r-fwvr
- NVD CVE-2026-69205
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