wp-includes/ms-functions.php in the Multisite WordPress API in WordPress before 4.7.1 does not properly choose random numbers for keys, which makes it easier for remote attackers to bypass intended access restrictions via a crafted (1) site signup or (2) user signup.
The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG’s algorithm is not cryptographically strong.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Wordpress | Wordpress | * | 4.7 (including) |
| Wordpress | Ubuntu | esm-apps/xenial | * |
| Wordpress | Ubuntu | precise | * |
| Wordpress | Ubuntu | trusty | * |
| Wordpress | Ubuntu | upstream | * |
| Wordpress | Ubuntu | xenial | * |
| Wordpress | Ubuntu | yakkety | * |
When a non-cryptographic PRNG is used in a cryptographic context, it can expose the cryptography to certain types of attacks. Often a pseudo-random number generator (PRNG) is not designed for cryptography. Sometimes a mediocre source of randomness is sufficient or preferable for algorithms that use random numbers. Weak generators generally take less processing power and/or do not use the precious, finite, entropy sources on a system. While such PRNGs might have very useful features, these same features could be used to break the cryptography.