CUPS copy_model() creates a predictable PPD tempfile without O_EXCL/O_NOFOLLOW (symlink TOCTOU, lp → root)
CVSS score
5.7
EPSS probability
%0.2
Risk score
0.0
Published
3 d ago
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Vulnerability description
CVE AI research
DayBreach AI Explanation
Verified against sourcesSources read
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Source agreement
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Evidence confidence
%55
Short explanation
CVE-2026-55480 affects OpenPrinting CUPS prior to version 2.4.20, where copy_model() creates predictable temporary PPD paths without O_EXCL or O_NOFOLLOW. A local attacker can exploit this symlink race condition to compromise file integrity or availability.
Successful exploitation allows the root-privileged CUPS scheduler to follow a planted symlink, overwriting or truncating target files with generated PPD data. This compromises system file integrity and service availability.
What should be done?
- Update OpenPrinting CUPS to version 2.4.20 or later
- Follow the vendor advisory and corresponding code commits
- Enforce strict access controls for printer administration
Chain of evidence and sources
OpenPrinting CUPS 2.4.20 öncesi sürümlerdeki copy_model() fonksiyonu, tahmin edilebilir geçici PPD dosyalarını O_EXCL veya O_NOFOLLOW olmadan açmaktadır.
Yarış durumu (TOCTOU) başarılı olursa root yetkileriyle çalışan zamanlayıcı symlink'i takip ederek hedef dosyayı üzerine yazabilir veya kesebilir.
Bu güvenlik açığı 2.4.20 sürümünde giderilmiştir.
Show the technical text from the sources
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.
CVSS vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H
CWE: CWE-59, CWE-377
Explanation produced with the local gemini-flash-lite-latest model. Numerical metrics and the KEV, patch and exploit statuses are not determined by AI.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-55480 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | openprinting | cups | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 5.7 | CVSS V3_1 | MEDIUM | CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H | CVE CNA |
| 5.7 | CVSS V31 | MEDIUM | CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H | NVD |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-55480 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-55480 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
CVSS Vector Radar Chart
5.7 / 10Vulnerability Scoring Details
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:HYama durumu bilinmiyor
Weakness Type (CWE & CAPEC)
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