CVE-2024-21635: Memos Access Tokens Stay Valid after User Password Change
Summary Access Tokens are used to authenticate application access. When a user changes their password, the existing list of Access Tokens stay valid instead of expiring. If a user finds that their account has been compromised, they can update their password.
The bad actor though will still have access to their account because the bad actor's Access Token stays on the list as a valid token. The user will have to manually delete the bad actor's Access Token to secure their account. The list of Access Tokens has a generic Description which makes it hard to pinpoint a bad actor in a list of Access Tokens.
Details
To improve Memos security, all Access Tokens will need to be revoked when a user changes their password. This removes the session for all the user's devices and prompts the user to log in again. You can treat the old Access Tokens as "invalid" because those Access Tokens were created with the older password.
PoC
1. Have 2 devices on hand 2. Log onto your Memos account on both devices. Notice how Access Tokens are created for each. 3. On one device, successfully change the password. Refresh the page on the 2nd device and notice how it doesn't log out the user. 4. On the 2nd device, change the password again. Refresh the page on the 1st device and notice how it doesn't log out the user.
Impact
A bad actor will still have access to the user's account because the Access Token does not expire on a password update. Having multi-factor authentication will vastly improve account security in Account Takeover cases instead of just relying on a password.
Other sources
Memos is a privacy-first, lightweight note-taking service that uses Access Tokens to authenticate application access. When a user changes their password, the existing list of Access Tokens stay valid instead of expiring. If a user finds that their account has been compromised, they can update their password. In versions up to and including 0.18.1, though, the bad actor will still have access to their account because the bad actor's Access Token stays on the list as a valid token. The user will have to manually delete the bad actor's Access Token to secure their account. The list of Access Tokens has a generic Description which makes it hard to pinpoint a bad actor in a list of Access Tokens. A known patched version of Memos isn't available. To improve Memos security, all Access Tokens will need to be revoked when a user changes their password. This removes the session for all the user's devices and prompts the user to log in again. One can treat the old Access Tokens as "invalid" because those Access Tokens were created with the older password.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2024-21635?
CVE-2024-21635 is considered a high-severity vulnerability due to its potential for unauthorized access.
How do I fix CVE-2024-21635?
To mitigate CVE-2024-21635, immediately expire old Access Tokens upon password changes and update to version 0.18.2 or later.
What versions of Memos are affected by CVE-2024-21635?
CVE-2024-21635 affects Memos versions up to and including 0.18.1.
What is the impact of CVE-2024-21635 on user accounts?
CVE-2024-21635 allows attackers to potentially maintain access to user accounts through valid Access Tokens even after a password change.
Is there a workaround for CVE-2024-21635?
A temporary workaround for CVE-2024-21635 is to manually revoke Access Tokens for affected accounts after a password change.