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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-55480
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-15 18:17:27 UTC
Updated2026-10-20 19:37:33 UTC
DescriptionOpenPrinting 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.

Risk And Classification

Primary CVSS: v3.1 5.7 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H

EPSS: 0.001570000 probability, percentile 0.044050000 (date 2026-10-20)

Problem Types: CWE-59 | CWE-377 | CWE-59 CWE-59: Improper Link Resolution Before File Access ('Link Following') | CWE-377 CWE-377: Insecure Temporary File

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H
3.1CNADECLARED5.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Openprinting Cups All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA OpenPrinting Cups affected < 2.4.20 Not specified

References

ReferenceSourceLinkTags
github.com/OpenPrinting/cups/security/advisories/GHSA-jj94-x3qh-ffp9 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com Exploit, Patch, Vendor Advisory
github.com/OpenPrinting/cups/commit/f6a11dae0f0f3b748fbca931e237be03ffe8... [email protected] github.com Patch
github.com/OpenPrinting/cups/commit/98adfd855950e806508f961d5438ad32e26a... [email protected] github.com Patch
github.com/OpenPrinting/cups/releases/tag/v2.4.20 [email protected] github.com Release Notes
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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