Overview
This article details a security vulnerability, identified as CVE-2024-21635, affecting Memos, a privacy-first, lightweight note-taking service. The vulnerability resides in the handling of Access Tokens after a user changes their password. Specifically, existing Access Tokens remain valid even after a password change, potentially allowing malicious actors to maintain unauthorized access to a compromised account.
Technical Details
Memos relies on Access Tokens for authentication. When a user changes their password, the application *should* revoke all existing Access Tokens, forcing a re-authentication process. However, versions up to and including 0.18.1 fail to do so. This means that if an attacker has gained access to an account and obtained an Access Token, changing the password alone will *not* invalidate the attacker’s access. The attacker will retain access until the Access Token is manually revoked by the user. Furthermore, the default descriptions for Access Tokens within Memos are generic, making it difficult to identify and revoke malicious tokens.
CVSS Analysis
Currently, a CVSS score and severity rating are not available for CVE-2024-21635. The impact of this vulnerability depends on the sensitivity of the data stored within Memos and the likelihood of an account being compromised. Given the potential for unauthorized data access, it is prudent to treat this vulnerability with caution.
Possible Impact
Successful exploitation of this vulnerability could have the following impacts:
- Unauthorized Access to Notes: An attacker with a valid Access Token could access, modify, or delete a user’s notes without their knowledge or consent.
- Data Breach: Sensitive information stored within Memos could be exposed, leading to a data breach.
- Privacy Violation: User privacy could be compromised due to unauthorized access to personal notes and information.
Mitigation or Patch Steps
As of the publication date of this article, a known patched version of Memos addressing CVE-2024-21635 is not yet available. However, the following steps can be taken to mitigate the risk:
- Manually Revoke Access Tokens: Regularly review the list of Access Tokens associated with your Memos account and revoke any tokens that are unfamiliar or suspicious.
- Password Reset and Token Revocation: If you suspect your account has been compromised, immediately change your password and *manually revoke all existing Access Tokens*.
- Monitor for Updates: Keep an eye on the Memos GitHub repository and official communication channels for announcements regarding a patched version. Upgrade to the latest version as soon as it becomes available.
The proposed solution is that all Access Tokens should be revoked whenever a user changes their password. This will force a re-authentication and invalidate any tokens created before the password change.
