The flaw stems from the error_description parameter in Gainsight Assist, which allows a Reflected Cross‑Site Scripting (XSS) injection. An attacker can craft a payload that is executed in a victim’s browser when the error_description value is reflected back in the response. Key detail from the official description: "The error_description parameter is vulnerable to Reflected XSS."

The vulnerability affects the Gainsight Assist product from Gainsight. The exact version range is not specified in the available data, so all installations of Gainsight Assist should be reviewed to determine whether they are exposed.

The CVSS score of 6.1 indicates a moderate severity. The EPSS score is not available, and the vulnerability is not listed in the CISA KEV catalog. Attackers must supply a malicious value for error_description, typically via a URL, and can steer the browser to execute the injected content; this is a client‑side attack. The description notes that a Safari‑specific onpagereveal payload can bypass domain WAF protections, potentially increasing the likelihood of successful exploitation for browsers that support this technique.