The vulnerability is a reflected cross‑site scripting flaw in Retool before version 3.88.0. An attacker can supply a URL that points to a crafted SVG file via the url parameter of the /api/imageProxy endpoint. The service returns the SVG content without a content‑security‑policy header, allowing embedded JavaScript to run in anyone who loads the response in their browser. The flaw permits arbitrary script execution with the privileges of the victim’s session, potentially enabling data theft or further compromise. The weakness is classified as CWE‑79.

Affected vendors and products include Retool deployments running any release prior to 3.88.0. All versions that expose the /api/imageProxy route may be vulnerable, regardless of the hosting environment or network segmentation. The advisory specifically references Retool 3.88.0 as the fix release.

The CVSS base score is 5.1, which denotes a moderate risk. The EPSS score is unavailable, so the current probability of exploitation is uncertain. The vulnerability is not listed in the CISA KEV catalog. Attackers can exploit it by placing a malicious SVG link or embedding the imageProxy URL in a malicious page and luring victims to load it. Because the endpoint is unauthenticated, any user with a Retool session who accesses the proxy response is at risk. No public exploit code is documented, but the Shadowserver Foundation observed exploitation on 2024‑10‑15.