SimpleSAMLphp-casserver is a CAS 1.0 and 2.0 compliant CAS server in the form of a SimpleSAMLphp module. Prior to version 7.0.3, simplesamlphp-module-casserver builds file paths for the file-based CAS ticket store by directly concatenating the configured ticket directory with an attacker-controlled ticket identifier. Public CAS validation/proxy endpoints pass attacker-controlled ticket / pgt query parameters into this store. In deployments using FileSystemTicketStore, a remote attacker can use path traversal sequences such as ../target.serialized to make the CAS server read and unserialize files outside the ticket directory. In the CAS 1.0 validation flow, the same attacker-selected path is also passed to deleteTicket() immediately after getTicket() returns, which can delete the target file when it is readable by the PHP process, deletable under the PHP process filesystem permissions, and unserializes to a value compatible with the ?array return type. This issue has been patched in version 7.0.3.

Affected: Packagist: simplesamlphp/simplesamlphp-module-casserver

## Summary

`simplesamlphp-module-casserver` builds file paths for the file-based CAS ticket store by directly concatenating the configured ticket directory with an attacker-controlled ticket identifier. Public CAS validation/proxy endpoints pass attacker-controlled `ticket` / `pgt` query parameters into this store.

In deployments using `FileSystemTicketStore`, a remote attacker can use path traversal sequences such as `../target.serialized` to make the CAS server read and unserialize files outside the ticket directory. In the CAS 1.0 validation flow, the same attacker-selected path is also passed to `deleteTicket()` immediately after `getTicket()` returns, which can delete the target file when it is readable by the PHP process, deletable under the PHP process filesystem permissions, and unserializes to a value compatible with the `?array` return type.

### Preconditions

The demonstrated issue requires:

- the `casserver` module to be enabled; - the file-based ticket store to be configured (`FileSystemTicketStore`); - public CAS validation/proxy endpoints to be reachable; - the PHP process to have filesystem permissions for the target path. - for the demonstrated CAS 1.0 deletion impact, `getTicket()` must return without throwing; practically, the target file must contain serialized PHP data that unserializes to a value compatible with the `?array` return type, such as an array or null. Full CAS semantic validation is not required for deletion in CAS 1.0 because `deleteTic…