What is CVE-2019-19389?

CVE-2019-19389 is a medium-severity vulnerability in Jetbrains Ktor, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 5.4/10. Published 2019-12-26.

How severe is CVE-2019-19389?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Vulnerability in Jetbrains Ktor

CVE-2019-19389

JetBrains Ktor framework before version 1.2.6 was vulnerable to HTTP Response Splitting.

Published 2019-12-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.008 (56.8th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 56.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Jetbrains Ktor

Weakness classification (CWE)

CWE-74 — Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection)

References

github.com/ktorio/ktor/pull/1408 (Patch, Third Party Advisory, Mitigation)
gist.github.com/JLLeitschuh/6792947ed57d589b08c1cc8b666c7737 (Exploit, Third Party Advisory)
twitter.com/JLLeitschuh/status/1210256191110230017 (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2019-19389?: CVE-2019-19389 is a medium-severity vulnerability in Jetbrains Ktor, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 5.4/10. Published 2019-12-26.
How severe is CVE-2019-19389?: Medium severity. CVSS v3 base score is 5.4 out of 10.