CVE-2026-69205
Http4s: Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling)
- 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, 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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High8.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N |
| NVDNVD · Deferred | 3.1 | High8.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.48% · top 58% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.7.
Weakness
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Mavenorg.http4s:http4s-ember-core_2.12GHSA-9998-894r-fwvr (opens in a new tab)
- Mavenorg.http4s:http4s-ember-core_2.13GHSA-9998-894r-fwvr (opens in a new tab)
- Mavenorg.http4s:http4s-ember-core_3GHSA-9998-894r-fwvr (opens in a new tab)
References (4)
- https://github.com/http4s/http4s/security/advisories/GHSA-9998-894r-fwvr (opens in a new tab)x_refsource_CONFIRM
- https://github.com/http4s/http4s/commit/5e88b2e7b4e6ea2f0c61040a4bc9de0d73e51217 (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-9998-894r-fwvr (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-2026-69205)Record last updated .