kaml provides YAML support for kotlinx.serialization. Prior to version 0.53.0, applications that use kaml to parse untrusted input containing anchors and aliases may consume excessive memory and crash. Version 0.53.0 and later default to refusing to parse YAML documents containing anchors and aliases. There are no known workarounds.

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.