CVE-2024-5953: 389-ds-base: malformed userpassword hash may cause denial of service
A denial of service vulnerability was found in 389-ds-base ldap server. This issue may allow an authenticated user to cause a server crash or hang while authenticating with an user having a malformed userPassword. By default only the administrator may directly add hashed password that can trigger the issue. But if nsslapd-allow-hashed-passwords config parameter is turned on, any user can trigger the issue.
The problem is triggered by adding a password to an user using the hashed format (with a hash value too long for the specified hash scheme) Then later on when trying to authenticate on that user its triggers the buffer overflow
By default, only administrators are allowed to add hashed passwords but there is a configuration parameter (nsslapd-allow-hashed-passwords) allowing any users to add hashed passwords and potentially trigger the DoS.
This vulnerability affects versions: >= 1.3.7.2
Other sources
A denial of service vulnerability was found in the 389-ds-base LDAP server. This issue may allow an authenticated user to cause a server denial of service while attempting to log in with a user with a malformed hash in their password.
— NVD
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Disable the nsslapd-allow-hashed-passwords config parameter so that only administrators can add hashed passwords and arbitrary users cannot trigger the denial of service by adding malformed long hashes.
389-ds-base LDAP server (nsslapd-allow-hashed-passwords) nsslapd-allow-hashed-passwords = off/disabled - Compensating control
If hashed-password ingestion must remain enabled, restrict the ability to add userPassword values in hashed format to administrators only (do not allow general/any users to add hashed passwords).
Event History
Frequently Asked Questions
What is the severity of CVE-2024-5953?
CVE-2024-5953 is classified as a denial of service vulnerability that can lead to server crashes.
How do I fix CVE-2024-5953?
To fix CVE-2024-5953, it is recommended to upgrade to the latest patched version of 389-ds-base.
Who is affected by CVE-2024-5953?
CVE-2024-5953 affects users of the 389-ds-base LDAP server version 1.3.7.2 and later.
What causes the CVE-2024-5953 vulnerability?
CVE-2024-5953 is caused by the server crashing or hanging when an authenticated user attempts to authenticate with a malformed userPassword.
Can unauthenticated users exploit CVE-2024-5953?
No, CVE-2024-5953 requires an authenticated user to exploit the vulnerability.