The secureCompare method in lib/SimpleSAML/Utils/Crypto.php in SimpleSAMLphp 1.14.13 and earlier, when used with PHP before 5.6, allows attackers to conduct session fixation attacks or possibly bypass authentication by leveraging missing character conversions before an XOR operation.
Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Simplesamlphp | Simplesamlphp | * | 1.14.13 (including) |
| Simplesamlphp | Ubuntu | esm-apps/xenial | * |
| Simplesamlphp | Ubuntu | trusty | * |
| Simplesamlphp | Ubuntu | upstream | * |
| Simplesamlphp | Ubuntu | xenial | * |
| Simplesamlphp | Ubuntu | zesty | * |
Such a scenario is commonly observed when: