Impact OctoPrint versions up to and including 1.11.7 as well as 2.0.0rc1 and 2.0.0rc2 are affected by a vulnerability that allows injection of arbitrary HTML and JavaScript into Suppressed Command notifications popups generated by the printer. An attacker who successfully convinces a victim to print a specially crafted file could exploit this issue to disrupt ongoing prints, extract information (including sensitive configuration settings, if the targeted user has the necessary permissions for that), or perform other actions on behalf of the targeted user within the OctoPrint instance. Patches The vulnerability has been patched in version 1.11.8 and 2.0.0rc3. Workaround OctoPrint administrators can mitigate the risk by disabling popups: - for Action Command notifications, set OctoPrint Settings -> Serial Connection -> Behaviour -> Sanity Checking -> Display notifications for suppressed commands to Never show notifications It is also strongly recommended to ensure that files being printed originate from trusted sources, and, whenever possible, are sliced with an application's own slicer. Credits This vulnerability was discovered and responsibly disclosed to OctoPrint by "Jacopo Tediosi" (https://github.com/jacopotediosi). Timeline 2026-03-18: Report received 2026-04-01: Report verified 2026-04-01: Fix ready for 2.0.0 2026-06-22: Fix backported to 1.11.x 2026-06-23: Fix released with 1.11.8 and 2.0.0rc3