CVE-2026-123318 · Package
NO FIX YET · SEE WHAT TO DO
Before Ktor 3.6.1, the CIO engine in JetBrains' Kotlin web framework could be tricked into request smuggling. An attacker can slip hidden requests past a front-end proxy and reach back-end logic they should not see.
first public Nov 6, 2026 · 1 source
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Services built on Ktor that use the CIO engine and sit behind a reverse proxy or load balancer are the ones at risk. Apps using other Ktor engines, or those with no proxy in front, are less exposed. The sources do not give further detail.
Not affected if ktor-3.6.1-or-later, no-front-proxy, non-cio-engine
Who cares jvm, kotlin, ktor, self-hosted
io.ktor:ktor-server-cio) in the server dependencies.3.6.1In JetBrains Ktor before 3.6.1 hTTP request smuggling was possible in the CIO engine
This page as .md · .json · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD data is provided by NIST and is public domain. Posts quoted belong to their authors.
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