CVE-2021-4235

Name: CVE-2021-4235
Creator: NVD / NIST
Published: 2022-12-27T22:15:11.96+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.5/10EPSS 0.41%

Last modified Jun 17, 2026

CVE-2021-4235 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. Due to unbounded alias chasing, a maliciously crafted YAML file can cause the system to consume significant system resources. If parsing user input, this may be used as a denial of service vector.. EPSS estimates a 0.41% chance of exploitation in the next 30 days.

Description

Due to unbounded alias chasing, a maliciously crafted YAML file can cause the system to consume significant system resources. If parsing user input, this may be used as a denial of service vector.

Metrics

CVSS 3.1

5.5/10

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

EPSS Probability

0.41%

33.2th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Yaml Project	Yaml	< 2.2.3

References

https://github.com/go-yaml/yaml/commit/bb4e33bf68bf89cad44d386192cbed201f35b241Patch, Third Party Advisory
https://github.com/go-yaml/yaml/pull/375Exploit, Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/07/msg00001.html
https://pkg.go.dev/vuln/GO-2021-0061Third Party Advisory
https://github.com/go-yaml/yaml/commit/bb4e33bf68bf89cad44d386192cbed201f35b241Patch, Third Party Advisory
https://github.com/go-yaml/yaml/pull/375Exploit, Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/07/msg00001.html
https://pkg.go.dev/vuln/GO-2021-0061Third Party Advisory

Timeline

Published: Dec 27, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-4235?

Due to unbounded alias chasing, a maliciously crafted YAML file can cause the system to consume significant system resources. If parsing user input, this may be used as a denial of service vector.

How severe is CVE-2021-4235?

CVE-2021-4235 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.41% probability of exploitation in the next 30 days.

How do I fix CVE-2021-4235?

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-2021-4235?

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

Scan your code now

Source: NVD / NIST