CVE-2026-55480CUPS copy_model() creates a predictable PPD tempfile without O_EXCL/O_NOFOLLOW (symlink TOCTOU, lp → root)

Açıklama

OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. Prior to 2.4.20, copy_model() in scheduler/ipp.c creates a predictable TempDir/<connection-number>.ppd path in an lp-group-writable directory and opens it as root without O_EXCL or O_NOFOLLOW. Exploitation requires an lp-group process able to write that directory to predict the connection-derived name and plant a symlink before the root open, while a privileged add-printer or modify-printer operation using a model PPD triggers copy_model(). The reporter treats an existing lp foothold and the privileged operation as distinct prerequisites, while the maintainer assesses high privileges because installing the relevant filter or administering the printer requires root or print-administrator access. If the race succeeds, the root scheduler follows the symlink and truncates or overwrites a root-writable target with generated PPD data, compromising file integrity or availability. This issue is fixed in version 2.4.20.

Veri: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Bilgiler kaynaktaki haliyle, İngilizce yayımlanır.

Etkilenen ürünler ve sürümler

Kaynaklar ve yamalar

• https://github.com/OpenPrinting/cups/security/advisories/GHSA-jj94-x3qh-ffp9 ExploitPatchVendor Advisory
• https://github.com/OpenPrinting/cups/commit/98adfd855950e806508f961d5438ad32e26aac62 Patch
• https://github.com/OpenPrinting/cups/commit/f6a11dae0f0f3b748fbca931e237be03ffe8e48e Patch
• https://github.com/OpenPrinting/cups/releases/tag/v2.4.20 Release Notes