This vulnerability is an Insecure Direct Object Reference in Craft Commerce’s cart functionality. The CartController accepts a user-supplied 32-character cart number and loads the corresponding cart without verifying ownership. As a result, an attacker who knows or can guess a cart ID can hijack that session, modify the cart contents, and potentially access or expose personally identifiable information. The weakness is classified as CWE‑639, an Information Exposure through IDOR.

The flaw is present in all versions of CraftCommerce before 4.11.0 and 5.6.0. The affected product is CraftCMS:Commerce, which is identified in the CPE as cpe:2.3:a:craftcms:craft_commerce:*:*:*:*:*:craft_cms:*:*. Any deployment running one of the affected versions is vulnerable.

The CVSS score of 6.3 indicates moderate severity, while the EPSS score of less than 1% shows a low likelihood of automated exploitation at present. The vulnerability is not listed in the CISA KEV catalog, suggesting it has not been widely exploited publicly. Attackers gain access by sending a crafted HTTP request containing a cart number; no additional authentication is required beyond knowing or guessing a valid ID. The risk is therefore moderate due to the potential for PII exposure and the straightforward exploitation path, but it is tempered by the low probability of exploitation and lack of widespread advisories.