CVE-2021-39194

Name: CVE-2021-39194
Creator: NVD / NIST
Published: 2021-09-07T20:15:08.193+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.60%

Last modified Jun 17, 2026

CVE-2021-39194 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. kaml is an open source implementation of the YAML format with support for kotlinx.serialization. In affected versions attackers that could provide arbitrary YAML input to an application that uses kaml could cause the application to endlessly loop while parsing the input. EPSS estimates a 1.60% chance of exploitation in the next 30 days.

Description

kaml is an open source implementation of the YAML format with support for kotlinx.serialization. In affected versions attackers that could provide arbitrary YAML input to an application that uses kaml could cause the application to endlessly loop while parsing the input. This could result in resource starvation and denial of service. This only affects applications that use polymorphic serialization with the default tagged polymorphism style. Applications using the property polymorphism style are not affected. YAML input for a polymorphic type that provided a tag but no value for the object would trigger the issue. Version 0.35.3 or later contain the fix for this issue.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

1.60%

72.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-835

Affected Software

Vendor	Product	Versions
Kaml Project	Kaml	< 0.35.3

References

https://github.com/charleskorn/kaml/commit/e18785d043fc6324c81e968aae9764b4b060bc6aPatch, Third Party Advisory
https://github.com/charleskorn/kaml/issues/179Exploit, Patch, Third Party Advisory
https://github.com/charleskorn/kaml/security/advisories/GHSA-fmm9-3gv8-58f4Exploit, Third Party Advisory
https://github.com/charleskorn/kaml/commit/e18785d043fc6324c81e968aae9764b4b060bc6aPatch, Third Party Advisory
https://github.com/charleskorn/kaml/issues/179Exploit, Patch, Third Party Advisory
https://github.com/charleskorn/kaml/security/advisories/GHSA-fmm9-3gv8-58f4Exploit, Third Party Advisory

Timeline

Published: Sep 7, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-39194?

How severe is CVE-2021-39194?

CVE-2021-39194 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.60% probability of exploitation in the next 30 days.

How do I fix CVE-2021-39194?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-39194?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST