wp-admin/user-new.php in WordPress before 4.9.1 sets the newbloguser key to a string that can be directly derived from the user ID, which allows remote attackers to bypass intended access restrictions by entering this string.
Weakness
The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.
Affected Software
| Name |
Vendor |
Start Version |
End Version |
| Wordpress |
Wordpress |
* |
4.9 (including) |
| Wordpress |
Ubuntu |
artful |
* |
| Wordpress |
Ubuntu |
esm-apps/xenial |
* |
| Wordpress |
Ubuntu |
trusty |
* |
| Wordpress |
Ubuntu |
upstream |
* |
| Wordpress |
Ubuntu |
xenial |
* |
| Wordpress |
Ubuntu |
zesty |
* |
Potential Mitigations
- Use a well-vetted algorithm that is currently considered to be strong by experts in the field, and select well-tested implementations with adequate length seeds.
- In general, if a pseudo-random number generator is not advertised as being cryptographically secure, then it is probably a statistical PRNG and should not be used in security-sensitive contexts.
- Pseudo-random number generators can produce predictable numbers if the generator is known and the seed can be guessed. A 256-bit seed is a good starting point for producing a “random enough” number.
References