CVE-2018-1000544 — rubyzip
CRITICALCVE-2018-1000544 is a critical-severity (CVSS 9.8) CWE-59 vulnerability in rubyzip. 1 public exploit reference exists, so weaponization risk is real. A fix is available for rubyzip — see the affected versions and patch details below.
Rubyzip gem contains a Directory Traversal vulnerability in zip file component
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2018-1000544 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
rubyzipReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
rubyzip gem rubyzip version 1.2.1 and earlier contains a Directory Traversal vulnerability in Zip::File component that can result in write arbitrary files to the filesystem. This attack appear to be exploitable via If a site allows uploading of .zip files , an attacker can upload a malicious file that contains symlinks or files with absolute pathnames "../" to write arbitrary files to the filesystem..
This is similar to CVE-2017-5946 which was patched in 1.2.1 but the fix in that case was incomplete.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rubyzip | all versions | 1.2.2bundle update rubyzip --conservative |
Affected Products
debian linuxdebiancloudformsredhatrubyziprubyzip_projectResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rubyzip, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rubyzip to 1.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-1000544 is resolved across your whole dependency graph.
Workarounds
Treat uploaded files as untrusted until proven otherwise: validate the actual content type rather than the supplied extension, store uploads outside the web root on a volume mounted without execute permission, and rename them to server-generated identifiers so an attacker cannot choose the path a request will later resolve.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| CloudForms Management Engine 5.9 | ansible-tower-0:3.2.7-1.el7at | RHSA-2018:3466 |
Frequently Asked Questions
Is CVE-2018-1000544 in your dependencies?
Find it across RubyGems, including transitive dependencies.