CVE-2021-29437: ScratchOAuth2 is an Oauth implementation for Scratch

Q: How do I fix CVE-2021-29437?

scratchoauth2: upgrade to 2021-04-13. Exact commands for each OS are on this page.

Q: Is CVE-2021-29437 being exploited?

CVE-2021-29437 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-29437 affect?

CVE-2021-29437 affects scratchoauth2. Severity is high (CVSS 8.0). 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

This month

HIGH 8.0UPGRADE

CVE-2021-29437 is a high-severity flaw (CVSS 8.0) affecting scratchoauth2. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 the

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.0 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 43%)
CISA exploited list	No
Weakness	CWE-863
Published	2021-04-13
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: scratchoauth2 project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-04-13 20:15 UTCPublished CVE record published
2026-06-17 03:47 UTCUpdated Record last modified

scratchoauth2 project scratchoauth2 UPGRADE

Affected: < 2021-04-13

Fixed in: 2021-04-13

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy scratchoauth2 || rpm -q scratchoauth2 || scratchoauth2 --version

2. UPGRADE to 2021-04-13 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade scratchoauth2

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade scratchoauth2

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-29437?

scratchoauth2: upgrade to 2021-04-13. Exact commands for each OS are on this page.

Is CVE-2021-29437 being exploited?

CVE-2021-29437 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-29437 affect?

CVE-2021-29437 affects scratchoauth2. Severity is high (CVSS 8.0). 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

How urgent is CVE-2021-29437?

Priority 42/100. High severity

Related CVEs

CVE-2021-46251 MEDIUM 6.1 UPGRADE A reflected cross-site scripting (XSS) in ScratchOAuth2 before commit 1603f04e44ef67dde6ccffe866d2dca16defb293
CVE-2021-46250 CRITICAL 10.0 UPGRADE An issue in SOA2Login::commented of ScratchOAuth2 before commit a91879bd58fa83b09283c0708a1864cdf067c64a allow
CVE-2021-46249 MEDIUM 6.5 UPGRADE An authorization bypass exploited by a user-controlled key in SpecificApps REST API in ScratchOAuth2 before co

References

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