High severity vulnerability that affects YamlDotNet and YamlDotNet.Signed

published 2018-07-13 8 y ago modified 2026-06-17 4 mo ago also GHSA-rpch-cqj9-h65r , EUVD-2018-0686

cvss: 7.8; version 3.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.5%; EPSS 1.5% chance of exploitation in 30 days, percentile 73%
public exploits: 0; none known

YamlDotNet version 4.3.2 and earlier contains a Insecure Direct Object Reference vulnerability in The default behavior of Deserializer.Deserialize() will deserialize user-controlled types in the line "currentType = Type.GetType(nodeEvent.Tag.Substring(1), throwOnError: false);" and blindly instantiates them. that can result in Code execution in the context of the running process. This attack appear to be exploitable via Victim must parse a specially-crafted YAML file. This vulnerability appears to have been fixed in 5.0.0.

Patch / fix

fixed in 2

nuget YamlDotNet 5.0.0
nuget YamlDotNet.Signed 5.0.0

Exploit prediction

1.47% chance of exploitation in the next 30 days, higher than 73% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.0	7.8	CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD	2.0	6.8	AV:N/AC:M/Au:N/C:P/I:P/A:P
GitHub	3.0	7.8	CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
nuget	YamlDotNet	<5.0.0	5.0.0
nuget	YamlDotNet.Signed	<5.0.0	5.0.0

Classification

Weakness

CWE-502 Deserialization of Untrusted Data
CWE-639 Authorization Bypass Through User-Controlled Key

References

github.com /aaubry/YamlDotNet#version-500
web, third-party-advisory
github.com /aaubry/YamlDotNet/blob/f96b7cc40a0498f8bafdeb49df3aa23aa2c60993/YamlDotNet/Serialization/NodeTypeResolvers/Ty
web, third-party-advisory
nvd.nist.gov /vuln/detail/CVE-2018-1000210
advisory
github.com /advisories/GHSA-rpch-cqj9-h65r
advisory

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary