CVE-2020-26236: In ScratchVerifier before commit a603769, an attacker can hijack the verification process to log into someone else's account on any site that uses Scr...

Description

In ScratchVerifier before commit a603769, an attacker can hijack the verification process to log into someone else's account on any site that uses ScratchVerifier for logins. A possible exploitation would follow these steps: 1. User starts login process. 2. Attacker attempts login for user, and is given the same verification code. 3. User comments code as part of their normal login. 4. Before user can, attacker completes the login process now that the code is commented. 5. User gets a failed login and attacker now has control of the account. Since commit a603769 starting a login twice will generate different verification codes, causing both user and attacker login to fail. For clients that rely on a clone of ScratchVerifier not hosted by the developers, their users may attempt to finish the login process as soon as possible after commenting the code. There is no reliable way for the attacker to know before the user can finish the process that the user has commented the code, so this vulnerability only really affects those who comment the code and then take several seconds before finishing the login.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS Probability

0.94%

56.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-287

Affected Software

Vendor	Product	Versions
Scratchverifier	Scratchverifier	< a603769

References

https://github.com/ScratchVerifier/ScratchVerifier/commit/a603769010abf8c1bede91af46e4945314e4aa4aPatch, Third Party Advisory
https://github.com/ScratchVerifier/ScratchVerifier/security/advisories/GHSA-99cr-hvf7-85g9Third Party Advisory
https://github.com/ScratchVerifier/ScratchVerifier/commit/a603769010abf8c1bede91af46e4945314e4aa4aPatch, Third Party Advisory
https://github.com/ScratchVerifier/ScratchVerifier/security/advisories/GHSA-99cr-hvf7-85g9Third Party Advisory

Timeline

Published: Nov 20, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-26236?

In ScratchVerifier before commit a603769, an attacker can hijack the verification process to log into someone else's account on any site that uses ScratchVerifier for logins. A possible exploitation would follow these steps: 1. User starts login process. 2. Attacker attempts login for user, and is given the same verification code. 3. User comments code as part of their normal login. 4. Before user can, attacker completes the login process now that the code is commented. 5. User gets a failed login and attacker now has control of the account. Since commit a603769 starting a login twice will generate different verification codes, causing both user and attacker login to fail. For clients that rely on a clone of ScratchVerifier not hosted by the developers, their users may attempt to finish the login process as soon as possible after commenting the code. There is no reliable way for the attacker to know before the user can finish the process that the user has commented the code, so this vulnerability only really affects those who comment the code and then take several seconds before finishing the login.

How severe is CVE-2020-26236?

CVE-2020-26236 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.94% probability of exploitation in the next 30 days.

How do I fix CVE-2020-26236?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.