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CVE-2018-1000544: rubyzip gem rubyzip version 1.2.1 and earlier contains a Directory Traversal vulnerability in Zip::File compon

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This week
CRITICAL 9.8REMOTEWATCHLISTUPGRADEMITIGATEDOWNGRADE

CVE-2018-1000544 is a critical-severity flaw (CVSS 9.8) affecting rubyzip, debian linux, cloudforms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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..

Why this priority

  • Critical severity
  • EPSS top 9%: very likely to be exploited
  • Public exploit reference
  • Remotely exploitable, no login, no user action
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score9.8 (Critical)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance4.4% (top 9%)
CISA exploited listNo
WeaknessCWE-59, CWE-434
Published2018-06-26
Last modified2026-06-17
Publisher (CNA): MITRE · Vendor: debian · redhat · rubyzip project

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Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

rubyzip project rubyzip UPGRADE
Affected: <= 1.2.1
Fixed in: newer than 1.2.1
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy rubyzip || rpm -q rubyzip || rubyzip --version
2. UPGRADE to newer than 1.2.1 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade rubyzip
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade rubyzip
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
debian debian linux MITIGATE
Affected: 8.0 · 9.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 8.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
redhat cloudforms DOWNGRADE
Affected: 4.6
Fixed in: no fixed release known
Safe to downgrade to: a release before 4.6
1. Check installed version
apt-cache policy cloudforms || rpm -q cloudforms || cloudforms --version
2. No fixed release: DOWNGRADE to a release before 4.6 (Debian / Ubuntu)
apt-cache madison cloudforms sudo apt install cloudforms=<VERSION_BEFORE_4.6> sudo apt-mark hold cloudforms
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list cloudforms sudo dnf downgrade cloudforms-<VERSION_BEFORE_4.6> sudo dnf versionlock add cloudforms
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.
RubyGems · rubyzip · FIXED · 1.2.2 · vulnerable: <= 1.2.1 · source
bundle update rubyzip bundle list | grep rubyzip
Fedora 46 · root · FIXED · 6.40.04-6.fc46 · FEDORA-2026-deac340022 · source
sudo dnf upgrade --advisory=FEDORA-2026-deac340022
Fedora ELN · man-pages · FIXED · 6.20-1.eln159 · FEDORA-2026-f1f5fb11b4 · source
sudo dnf upgrade --advisory=FEDORA-2026-f1f5fb11b4
Ubuntu 20.04 · ruby-zip · NOT AFFECTED
Ubuntu 22.04 · ruby-zip · NOT AFFECTED
Ubuntu 24.04 · ruby-zip · NOT AFFECTED
Ubuntu 24.10 · ruby-zip · NOT AFFECTED
Ubuntu 25.04 · ruby-zip · NOT AFFECTED
Debian 12 · ruby-zip · FIXED · 1.2.2-1
sudo apt update && sudo apt install --only-upgrade ruby-zip dpkg --compare-versions "$(dpkg-query -W -f='${Version}' ruby-zip)" ge "1.2.2-1" && echo PATCHED || echo STILL-VULNERABLE
Debian 13 · ruby-zip · FIXED · 1.2.2-1
sudo apt update && sudo apt install --only-upgrade ruby-zip dpkg --compare-versions "$(dpkg-query -W -f='${Version}' ruby-zip)" ge "1.2.2-1" && echo PATCHED || echo STILL-VULNERABLE

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2018-1000544?

rubyzip: upgrade to newer than 1.2.1; debian linux: mitigate or apply the listed mitigation; cloudforms: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-1000544 being exploited?

CVE-2018-1000544 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2018-1000544 affect?

CVE-2018-1000544 affects rubyzip, debian linux, cloudforms. Severity is critical (CVSS 9.8). 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 uploadin

How urgent is CVE-2018-1000544?

Priority 72/100. Critical severity; EPSS top 9%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

References

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