Auth bypass in Scratchoauth2 Project

CVE-2021-29437

ScratchOAuth2 is an Oauth implementation for Scratch. Any ScratchOAuth2-related data normally accessible and modifiable by a user can be read and modified by a third party. 1. Scratch user visits 3rd party site. 2. 3rd party site asks user for Scratch username. 3. 3rd party site pretends to be user and gets login code from ScratchOAuth2. 4. 3rd party site gives code to user and instructs them to post it on their profile. 5. User posts code on their profile, not knowing it is a ScratchOAuth2 login code. 6. 3rd party site completes login with ScratchOAuth2. 7. 3rd party site has full access to anything the user could do if they directly logged in. See referenced GitHub security advisory for patch notes and workarounds.

Vulnerability class: Broken Access Control

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.008 (55.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2021-29437: held from 0.008 to 0.008.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2021-29437?
CVE-2021-29437 is a high-severity vulnerability in Scratchoauth2 Project, classified under Incorrect Authorization. CVSS score: 8.0/10. Published 2021-04-13.
How severe is CVE-2021-29437?
High severity. CVSS v3 base score is 8.0 out of 10.