CVE-2026-95511

A privilege escalation vulnerability was found in CUPS when used with the cups-filters serial backend. A local user who is a member of the lpadmin group can configure a printer that uses a privileged serial backend. The CUPS scheduler does not restrict the path component of non-file device URIs, so the root-privileged backend can write attacker-controlled print data to an arbitrary file. This can be used to change security-sensitive CUPS configuration and ultimately achieve root code execution. Exploitation requires local lpadmin group membership and a serial backend binary installed with root-only permissions.

Not a vulnerability. Creating a serial queue that overwrites cups-files.conf requires membership in SystemGroups (lpadmin), which is an opt-in cupsd admin role granted by a superuser. No privilege boundary is crossed.

Not a vulnerability. Creating a serial queue that overwrites cups-files.conf requires membership in SystemGroups (lpadmin), which is an opt-in cupsd admin role granted by a superuser. No privilege boundary is crossed.

Rejected reason: Not a vulnerability. Creating a serial queue that overwrites cups-files.conf requires membership in SystemGroups (lpadmin), which is an opt-in cupsd admin role granted by a superuser. No privilege boundary is crossed.

These are all security issues fixed in the cups-filters-1.28.17-10.1 package on the GA media of openSUSE Tumbleweed.

This update for cups-filters fixes the following issues:

Changes in cups-filters:

• No longer provide the serial backend with 0700 permissions so cupsd does no longer run it as root but as usual as user 'lp' to avoid CVE-2026-95511 "Root arbitrary file overwrite via serial ... device-URI path" https://github.com/OpenPrinting/cups-filters/security/advisories/GHSA-m74w-wg6q-vvpj "lpadmin user can escalate privileges to root via printers that uses a privileged serial backend" (bsc#1282291) Note the general security advice in the section "Allow printer admin tasks for a normal user" in https://en.opensuse.org/SDB:CUPS_in_a_Nutshell

• No longer provide any other backend with 0700 permissions so cupsd does no longer run them as root but as usual as user 'lp' because running something as root by default is a generic security issue which we avoid now by default so the user must set less secure permissions manually only as specifically needed. In particular no longer provide /usr/lib/cups/backend/beh /usr/lib/cups/backend/cups-brf /usr/lib/cups/backend/implicitclass with 0700 permissions by default so in particular https://bugzilla.opensuse.org/show_bug.cgi?id=1178604 re-appears but security by default is mandatory nowadays, cf. the sections "Security: Make Things Not Just Work" and "Automated print queue setup via cups-browsed" in https://en.opensuse.org/SDB:CUPS_and_SANE_Firewall_settings

This update for cups-filters fixes the following issue:

• CVE-2026-95511: lpadmin user can escalate privileges to root via printers that uses a privileged serial backend (bsc#1282291).

This update for cups-filters fixes the following issue:

• CVE-2026-95511: lpadmin user can escalate privileges to root via printers that uses a privileged serial backend (bsc#1282291).