How severe is CVE-2020-5207?

CVE-2020-5207 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2020-5207 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-5207?

CVE-2020-5207 affects Jetbrains Ktor. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-5207?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-5207 published?

CVE-2020-5207 was published on 2020-01-27 and last updated on 2026-06-17.

CVE-2020-5207

CVE-2020-5207 is a medium-severity vulnerability in Jetbrains Ktor with a CVSS 3.x base score of 5.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-444.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
CVSS v2: 5.0
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-444
Affected product: Jetbrains Ktor
Published: 2020-01-27
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2020-5207?: 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.
How severe is CVE-2020-5207?: CVE-2020-5207 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2020-5207 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-5207?: CVE-2020-5207 affects Jetbrains Ktor. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-5207?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-5207 published?: CVE-2020-5207 was published on 2020-01-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:jetbrains:ktor:*:*:*:*:*:*:*:*

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