CVE-2020-5207
Request smuggling is possible in Ktor when both chunked TE and content length specified
HIGH
7.5
CVSS Score
Published: January 27, 2020 at 07:30 PM UTC
Updated: June 17, 2026 at 03:21 AM UTC
2 products affected across 2 vendorsKtorKtor
Using Ktor by Ktor.io?
Get instant alerts when new vulnerabilities affect Ktor - before attackers find them.
Real-time alertsTrack your software stackFree plan available
Severity
HIGH7.5
Exploit prediction
EPSS 0.8%
Description
In Ktor before 1.3.0, request smuggling is possible when running behind a proxy that doesn't handle Content-Length and Transfer-Encoding properly or doesn't handle \n as a headers separator.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
v < 1.3.0
Affected range stops below 1.3.0, so it looks safe — our inference, not a vendor statement
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
Patch and advisory references
References (2)
x_refsource_MISCPatchThird Party Advisory
Source: [email protected]
https://github.com/ktorio/ktor/pull/1547x_refsource_CONFIRMThird Party Advisory
Source: [email protected]
https://github.com/ktorio/ktor/security/advisories/GHSA-xrr9-rh8p-433vCVSS
- Attack Vector
- NETWORK
- Complexity
- LOW
- Privileges
- NONE
- User Interaction
- NONE
- Scope
- UNCHANGED
- Confidentiality
- NONE
- Integrity
- HIGH
- Availability
- NONE
Vector?
Quick Info
StatusMODIFIED
CWE
CWE-444
Get alerted
Stop reading CVE feeds looking for your own stack
Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.
Free plan, no card