CVE-2021-41194: Improper Access Control in jupyterhub-firstuseauthenticator
Impact
When JupyterHub is used with FirstUseAuthenticator, the vulnerability allows unauthorized access to any user's account if createusers=True and the username is known or guessed.
Patches
Upgrade to jupyterhub-firstuseauthenticator to 1.0, or apply patch https://github.com/jupyterhub/firstuseauthenticator/pull/38.patch
Workarounds
If you cannot upgrade, there is no complete workaround, but it can be mitigated.
If you cannot upgrade yet, you can disable user creation with c.FirstUseAuthenticator.createusers = False, which will only allow login with fully normalized usernames for already existing users prior to jupyterhub-firstuserauthenticator 1.0. If any users have never logged in with their normalized username (i.e. lowercase), they will still be vulnerable until you can patch or upgrade.
Other sources
FirstUseAuthenticator is a JupyterHub authenticator that helps new users set their password on their first login to JupyterHub. When JupyterHub is used with FirstUseAuthenticator, a vulnerability in versions prior to 1.0.0 allows unauthorized access to any user's account if createusers=True and the username is known or guessed. One may upgrade to version 1.0.0 or apply a patch manually to mitigate the vulnerability. For those who cannot upgrade, there is no complete workaround, but a partial mitigation exists. One can disable user creation with c.FirstUseAuthenticator.createusers = False, which will only allow login with fully normalized usernames for already existing users prior to jupyterhub-firstuserauthenticator 1.0.0. If any users have never logged in with their normalized username (i.e. lowercase), they will still be vulnerable until a patch or upgrade occurs.
Affected Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is the impact of CVE-2021-41194?
The vulnerability allows unauthorized access to any user's account.
How can the CVE-2021-41194 vulnerability be exploited?
Unauthorized users can gain access to any user's account.
Which versions of JupyterHub FirstUseAuthenticator are affected by CVE-2021-41194?
Versions prior to 1.0.0 are affected.
How can I fix the CVE-2021-41194 vulnerability?
Upgrade to JupyterHub FirstUseAuthenticator version 1.0.0 or later.
What is the Common Weakness Enumeration (CWE) of CVE-2021-41194?
The CWE of CVE-2021-41194 is 284.