Deserialization in Mit Scratch-Vm
CVE-2020-14000
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.
Vulnerability class: Insecure Deserialization
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.028 (86.1th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 86th percentile — 86.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.028 · newest: 0.028 · change: 0.000
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/LLK/scratch-vm/pull/2476 (Third Party Advisory)
- scratch.mit.edu/discuss/topic/422904/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2020-14000?
- CVE-2020-14000 is a critical-severity vulnerability in Mit Scratch-Vm, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2020-07-16.
- How severe is CVE-2020-14000?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2020-14000 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.