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TI-2020-04263 Aliases CVE-2020-5207GHSA-xrr9-rh8p-433v

Request smuggling is possible in Ktor when both chunked TE and content length specified

Priority LOW 34CWE-444Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · High · None
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub.

Summary

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.

Why it matters now

EPSS 0.00762 55th percentileScored 2026-11-07
Fix Fixed Ktor (Ktor.io): 1.3.0io.ktor:ktor-client-cio (Maven): 1.3.0+1 more product

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
Ktor.ioKtorbefore 1.3.01.3.0Patch availableCNA
—io.ktor:ktor-client-cio (Maven)before 1.3.01.3.0Patch availableGHSA-xrr9-rh8p-433v
—io.ktor:ktor-server-cio (Maven)before 1.3.01.3.0Patch availableGHSA-xrr9-rh8p-433v
  • Ktor VendorKtor.io Affected before 1.3.0 Fixed in 1.3.0 Patch available CNA
  • io.ktor:ktor-client-cio (Maven) Vendor— Affected before 1.3.0 Fixed in 1.3.0 Patch available GHSA-xrr9-rh8p-433v
  • io.ktor:ktor-server-cio (Maven) Vendor— Affected before 1.3.0 Fixed in 1.3.0 Patch available GHSA-xrr9-rh8p-433v

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:jetbrains:ktor:*:*:*:*:*:*:*:*before 1.3.0VulnerableJetBrains
  • cpe:2.3:a:jetbrains:ktor:*:*:*:*:*:*:*:* Versions before 1.3.0 Vulnerable ·JetBrains

Remediation

  • Fix · CNA Ktor (Ktor.io) Fixed in 1.3.0
  • Fix · GHSA-xrr9-rh8p-433v io.ktor:ktor-client-cio (Maven) Fixed in 1.3.0 Advisory →
  • Fix · GHSA-xrr9-rh8p-433v io.ktor:ktor-server-cio (Maven) Fixed in 1.3.0 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2020-5207
  2. 2026-10-03 Alias added: GHSA-xrr9-rh8p-433v

References

Patch 1

Advisory 2

  • TI-2023-24413 In JetBrains Ktor before 2.3.5 default configuration of ContentNegotiation with XML format was vulnerable to XXE CVSS 3.1CRITICAL 9.8
  • TI-2019-09527 JetBrains Ktor framework before 1.2.0-rc does not sanitize the username provided by the… CVSS 3.1CRITICAL 9.8
  • TI-2023-24414 In JetBrains Ktor before 2.3.5 server certificates were not verified CVSS 3.1CRITICAL 9.1
  • TI-2022-24056 In JetBrains Ktor before 2.3.0 path traversal in the `resolveResource` method was possible CVSS 3.1HIGH 7.5
  • TI-2022-12277 SHA1 implementation in JetBrains Ktor Native 2.0.0 was returning the same value. CVSS 3.1HIGH 8.7
  • TI-2019-07426 JetBrains Ktor framework (created using the Kotlin IDE template) versions before 1.1.0… CVSS 3.0HIGH 8.1
See all 20 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences