CVE-2021-41110

cwlviewer is a web application to view and share Common Workflow Language workflows. Versions prior to 1.3.1 contain a Deserialization of Untrusted Data vulnerability. Commit number f6066f09edb70033a2ce80200e9fa9e70a5c29de (dated 2021-09-30) contains a patch. There are no available workarounds aside from installing the patch. The SnakeYaml constructor, by default, allows any data to be parsed. To fix the issue the object needs to be created with a SafeConstructor object, as seen in the patch.

Weakness

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

Affected Software

Potential Mitigations

• Make fields transient to protect them from deserialization.
• An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/586.html

References

• https://github.com/common-workflow-language/cwlviewer/commit/f6066f09edb70033a2ce80200e9fa9e70a5c29de
• https://github.com/common-workflow-language/cwlviewer/security/advisories/GHSA-7g7j-f5g3-fqp7
• https://www.fatalerrors.org/a/analysis-of-the-snakeyaml-deserialization-in-java-security.html
• https://github.com/common-workflow-language/cwlviewer/commit/f6066f09edb70033a2ce80200e9fa9e70a5c29de
• https://github.com/common-workflow-language/cwlviewer/security/advisories/GHSA-7g7j-f5g3-fqp7
• https://www.fatalerrors.org/a/analysis-of-the-snakeyaml-deserialization-in-java-security.html