{"cve":"CVE-2021-29437","nvd":{"published":"2021-04-13T20:15:22.093","modified":"2026-06-17T03:47:38.407","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","score":6.8},"cwes":["CWE-863"],"references":["https://github.com/ScratchVerifier/ScratchOAuth2/commit/9220c2a77eda3df37a84486ad722f1ad0985d8e7","https://github.com/ScratchVerifier/ScratchOAuth2/security/advisories/GHSA-gvpg-23fh-8g75","https://github.com/ScratchVerifier/ScratchOAuth2/commit/9220c2a77eda3df37a84486ad722f1ad0985d8e7","https://github.com/ScratchVerifier/ScratchOAuth2/security/advisories/GHSA-gvpg-23fh-8g75"],"products":["scratchoauth2_project:scratchoauth2"],"source":"nvd","synced_at":"2026-10-19T21:17:01.373894544+00:00"},"epss":{"cve":"CVE-2021-29437","score":0.00806,"percentile":0.56805,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}