A vulnerability has been found in NYUCCL psiTurk up to 3.2.0 and classified as critical. This vulnerability affects unknown code of the file psiturk/experiment.py. The manipulation of the argument mode leads to improper neutralization of special elements used in a template engine. Using CWE to declare the problem leads to CWE-1336. The weakness was released 01/27/2023 as 517. The advisory is shared for download at github.com. This vulnerability was named CVE-2021-4315. The attack can only be initiated within the local network. Technical details are available. Furthermore, there is an exploit available. The exploit has been disclosed to the public and may be used. The current price for an exploit might be approx. USD $0-$5k at the moment. The MITRE ATT&CK project declares the attack technique as T1221. It is declared as proof-of-concept. It is possible to download the exploit at github.com. As 0-day the estimated underground price was around $0-$5k. Upgrading to version 3.2.1 is able to address this issue. The updated version is ready for download at github.com. The name of the patch is 47787e15cecd66f2aa87687bf852ae0194a4335f. The bugfix is ready for download at github.com. It is recommended to upgrade the affected component. A possible mitigation has been published even before and not after the disclosure of the vulnerability.