CVE-2018-6553· NVD / CVE Program· CNA canonical

AppArmor cupsd Sandbox Bypass Due to Use of Hard Links

The CUPS AppArmor profile incorrectly confined the dnssd backend due to use of hard links. A local attacker could possibly use this issue to escape confinement. This flaw affects versions prior to 2.2.7-1ubuntu2.1 in Ubuntu 18.04 LTS, prior to 2.2.4-7ubuntu3.1 in Ubuntu 17.10, prior to 2.1.3-4ubuntu0.5 in Ubuntu 16.04 LTS, and prior to 1.7.2-0ubuntu1.10 in Ubuntu 14.04 LTS.

HighCVSS 8.8 · v3.0—No exploit Fix available

Published: Aug 10, 2018
Updated: Jun 16, 2026
EPSS: 0.4% · 30th percentile
CWE: —

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Monitor

Low priority for now.

CVSS: 35 / 40 · 8.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.4%

Affected systems

Vendor	Product	CPE
cups	cups	cpe:2.3:a:cups:cups
canonical	ubuntu linux	cpe:2.3:o:canonical:ubuntu_linux
debian	debian linux	cpe:2.3:o:debian:debian_linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

canonical ubuntu linux14.04
canonical ubuntu linux16.04
canonical ubuntu linux17.10
canonical ubuntu linux18.04
cups cupsall versions
debian debian linux8.0
debian debian linux9.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (canonical). Independent of NVD's CPE analysis and usually ahead of it.

n/a cups
- unspecified and later · before 2.2.7-1ubuntu2.1affected
- unspecified and later · before 2.2.4-7ubuntu3.1affected
- unspecified and later · before 2.1.3-4ubuntu0.5affected
- unspecified and later · before 1.7.2-0ubuntu1.10affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	cups	before 2.2.8-5	2.2.8-5
Debian:8	cups	before 1.7.5-11+deb8u4	1.7.5-11+deb8u4
Debian:9	cups	before 2.2.1-8+deb9u2	2.2.1-8+deb9u2

Same product

cups: all records

Other highest-scoring records for the same primary product.

CVE-2015-1158The add_job function in scheduler/ipp.c in cupsd in CUPS before 2.0.3 performs incorrect free operations for multiple-value job-originating-
49Plan
CVE-2008-0882Double free vulnerability in the process_browse_data function in CUPS 1.3.5 allows remote attackers to cause a denial of service (daemon cra
42Plan
CVE-2007-4351Off-by-one error in the ippReadIO function in cups/ipp.c in CUPS 1.3.3 allows remote attackers to cause a denial of service (crash) via a cr
42Plan
CVE-2014-8166The browsing feature in the server in CUPS does not filter ANSI escape sequences from shared printer names, which might allow remote attacke
36Monitor
CVE-2005-4873Multiple stack-based buffer overflows in the phpcups PHP module for CUPS 1.1.23rc1 might allow context-dependent attackers to execute arbitr
31Monitor
CVE-2007-0720The CUPS service on multiple platforms allows remote attackers to cause a denial of service (service hang) via a "partially-negotiated" SSL
22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
debian:cups	2.2.8-5 · Debian:12	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Dan Bastone

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Someone with local access to the system can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector: Local
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Changed
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

—

CVSS vector

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

Fix✗ → ✓Sep 28, 2026, 10:48 PM UTC

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records