Request smuggling is possible when both chunked TE and content length specified
Impact
Request smuggling is possible when running behind a proxy that doesn't handle Content-Length and Transfer-Encoding properly or doesn't handle alone \n as a headers separator.
Patches
https://github.com/ktorio/ktor/pull/1547
Workarounds
None except migrating to a better proxy.
References
https://portswigger.net/web-security/request-smuggling https://tools.ietf.org/html/rfc7230#section-9.5
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | io.ktor:ktor-client-cio | < 1.3.0 | 1.3.0 |
| Java / Kotlin (Maven) | io.ktor:ktor-server-cio | < 1.3.0 | 1.3.0 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-444- Platform
- Java / Kotlin (Maven)
- Package
io.ktor:ktor-client-cio, io.ktor:ktor-server-cio- Disclosed
- 27.01.2020
- Updated
- 11.10.2026 12:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-xrr9-rh8p-433v - CC BY 4.0
Vulnerability history: io.ktor:ktor-client-cio
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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