# CVE-2026-55480: CUPS copy_model() creates a predictable PPD tempfile without O_EXCL/O_NOFOLLOW (symlink TOCTOU, lp → root) CVE-2026-55480 is fixed in 15 products on 1 platform, first by ALAS2023-2026-3415, released November 10, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-55480 - Priority: Routine - CVSS: 5.7 (Moderate) - EPSS: 0.0020 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Oct 17, 2026 - Weakness: Improper Link Resolution Before File Access ('Link Following') - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55480 ## Description When a printer is added or modified with a model PPD, the cupsd scheduler (running as root) calls copy_model() in scheduler/ipp.c, which writes the driver-generated PPD to a temporary file. The tempfile path is fully predictable (/number>.ppd, where con->number is the sequential client connection id) and is opened with open(tempfile, O_WRONLY | O_CREAT | O_TRUNC, 0600) -- without O_EXCL and without O_NOFOLLOW. TempDir (/var/spool/cups/tmp) is mode 01770 root:lp, i.e. writable by the lp group that print filters run under. An lp-group process can pre-plant a symlink at the predicted path pointing at any root-owned file; root follows the symlink and truncates/overwrites the target, giving an lp - root arbitrary-file-write primitive. The codebase's own cups/tempfile.c opens temporaries safely with O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW; copy_model() is the inconsistent outlier. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | cups amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-client amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-client-debuginfo amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-debuginfo amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-debugsource amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-devel amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-filesystem amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-ipptool amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-ipptool-debuginfo amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-libs amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-libs-debuginfo amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-lpd amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-lpd-debuginfo amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-printerapp amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | | Linux | cups-printerapp-debuginfo amzn 2023 | 1:2.4.20-1.amzn2023.0.1 | [ALAS2023-2026-3415](https://patchblox.com/security/data/fix/linux/alas2023-2026-3415.md) | Nov 10, 2026 | --- Data as of 2026-11-11T13:47:35Z UTC. 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