An argument injection flaw was found in CUPS. When email notification is configured, the CUPS scheduler accepts printer subscription requests that supply a mailto notify-recipient-uri. The mailto notifier passes the recipient address to the configured sendmail program without ensuring it cannot be interpreted as command-line options. A remote attacker who can reach the CUPS service could supply a crafted recipient value starting with "-" to influence sendmail behavior. Successful exploitation depends on the installed mail transfer agent and CUPS network exposure, and may lead to execution of attacker-controlled commands with the privileges of the CUPS service user.
https://github.com/OpenPrinting/cups/security/advisories/GHSA-r4wf-366f-f6g3
https://github.com/OpenPrinting/cups/commit/611d1bd
https://github.com/OpenPrinting/cups/commit/1244ed9
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-92637