Description
MIT Lifelong Kindergarten Scratch scratch-vm before 0.2.0-prerelease.20200714185213 loads extension URLs from untrusted project.json files with certain _ characters, resulting in remote code execution because the URL's content is treated as a script and is executed as a worker. The responsible code is getExtensionIdForOpcode in serialization/sb3.js. The use of _ is incompatible with a protection mechanism in older versions, in which URLs were split and consequently deserialization attacks were prevented. NOTE: the scratch.mit.edu hosted service is not affected because of the lack of worker scripts.
Remediation
References
https://github.com/LLK/scratch-vm/pull/2476
https://scratch.mit.edu/discuss/topic/422904/?page=1#post-4223443
Related Vulnerabilities
CVE-2019-10431 Vulnerability in maven package org.jenkins-ci.plugins:script-security
CVE-2021-23358 Vulnerability in maven package org.webjars.npm:underscore
CVE-2019-1020012 Vulnerability in npm package parse-server
CVE-2022-23539 Vulnerability in maven package org.webjars.npm:jsonwebtoken
CVE-2020-8244 Vulnerability in maven package org.webjars.npm:bl