CVE-2026-55480 — CUPS copy_model() creates a predictable PPD tempfile without O_EXCL/O_NOFOLLOW (symlink TOCTOU, lp → root)
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.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Openprinting Cups).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (file handling), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Openprinting | Cups | version < 2.4.20 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 5.7 | CVSS 3.1 | Medium | 0.5 | 5.2 | security-advisories@github.com via NIST National Vulnerability Database |
| 5.7 | CVSS 3.1 | Medium | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H (score shown at the top: security-advisories@github.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Monitor file creation in web directories and paths with traversal sequences (../).
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · openprinting/cups
- Record published
- CVSS changed · 5.7
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× References added · Oct 15, 2026 – Oct 15, 2026
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
4 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-61702 OpenPrinting CUPS: root-side banner file disclosure 5h
- Low CVE-2026-55453 CUPS ipp backend status-line injection can update queue PPD and lead to conditional RCE as lp via foomatic-rip 5h
- Low CVE-2026-55467 CUPS fax option values bypass the CVE-2026-34980 control-character sanitizer (incomplete fix) 5h
- Medium CVE-2026-107888 OpenPrinting CUPS before 2.4.20 contains a NULL pointer dereference in cupsdCheckJobs() when a... 6d
- Low CVE-2026-107890 NULL Pointer Dereference in Openprinting Cups 6d
- Low CVE-2026-107886 Double Free in Openprinting Cups 6d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No FIRST EPSS score.
- No fixed version, patch or mitigation documented.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-55480 is "CUPS copy_model() creates a predictable PPD tempfile without O_EXCL/O_NOFOLLOW (symlink TOCTOU, lp → root)", rated Medium. It affects Cups (Openprinting); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.7 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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