CVE-2018-8780

CVE-2018-8780 is a critical-severity vulnerability in Ruby-lang Ruby with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.

Key facts

• Severity: Critical (CVSS 3.x base score 9.1)
• CVSS v2: 7.5
• EPSS exploit prediction: 10% (95th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-22
• Affected product: Ruby-lang Ruby
• Published: 2018-04-03
• Last modified: 2026-06-17

Description

In Ruby before 2.2.10, 2.3.x before 2.3.7, 2.4.x before 2.4.4, 2.5.x before 2.5.1, and 2.6.0-preview1, the Dir.open, Dir.new, Dir.entries and Dir.empty? methods do not check NULL characters. When using the corresponding method, unintentional directory traversal may be performed.

Frequently asked questions

What is CVE-2018-8780?

In Ruby before 2.2.10, 2.3.x before 2.3.7, 2.4.x before 2.4.4, 2.5.x before 2.5.1, and 2.6.0-preview1, the Dir.open, Dir.new, Dir.entries and Dir.empty? methods do not check NULL characters. When using the corresponding method, unintentional directory traversal may be performed.

How severe is CVE-2018-8780?

CVE-2018-8780 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2018-8780 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-8780?

CVE-2018-8780 primarily affects Ruby-lang Ruby. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-8780?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2018-8780 published?

CVE-2018-8780 was published on 2018-04-03 and last updated on 2026-06-17.

References

• http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00036.html
• http://www.securityfocus.com/bid/103739
• http://www.securitytracker.com/id/1042004
• https://access.redhat.com/errata/RHSA-2018:3729
• https://access.redhat.com/errata/RHSA-2018:3730
• https://access.redhat.com/errata/RHSA-2018:3731
• https://access.redhat.com/errata/RHSA-2019:2028
• https://access.redhat.com/errata/RHSA-2020:0542
• https://access.redhat.com/errata/RHSA-2020:0591
• https://access.redhat.com/errata/RHSA-2020:0663
• https://lists.debian.org/debian-lts-announce/2018/04/msg00023.html
• https://lists.debian.org/debian-lts-announce/2018/04/msg00024.html
• https://lists.debian.org/debian-lts-announce/2018/07/msg00012.html
• https://usn.ubuntu.com/3626-1/
• https://www.debian.org/security/2018/dsa-4259
• https://www.ruby-lang.org/en/news/2018/03/28/poisoned-nul-byte-dir-cve-2018-8780/
• https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-2-10-released/
• https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-3-7-released/
• https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-4-4-released/
• https://www.ruby-lang.org/en/news/2018/03/28/ruby-2-5-1-released/

Affected products (8)

• cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
• cpe:2.3:a:ruby-lang:ruby:2.6.0:preview1:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

More vulnerabilities in Ruby-lang Ruby

• CVE-2009-4124 — Critical (CVSS 10.0): Heap-based buffer overflow in the rb_str_justify function in string.c in Ruby 1.9.1 before 1.9.1-p376 allows…
• CVE-2008-2662 — Critical (CVSS 10.0): Multiple integer overflows in the rb_str_buf_append function in Ruby 1.8.4 and earlier, 1.8.5 before 1.8.5-p231, 1.8.6…
• CVE-2008-2663 — Critical (CVSS 10.0): Multiple integer overflows in the rb_ary_store function in Ruby 1.8.4 and earlier, 1.8.5 before 1.8.5-p231, 1.8.6…
• CVE-2016-2338 — Critical (CVSS 9.8): An exploitable heap overflow vulnerability exists in the Psych::Emitter start_document function of Ruby. In…
• CVE-2022-28738 — Critical (CVSS 9.8): A double free was found in the Regexp compiler in Ruby 3.x before 3.0.4 and 3.1.x before 3.1.2. If a victim attempts to…
• CVE-2011-4121 — Critical (CVSS 9.8): The OpenSSL extension of Ruby (Git trunk) versions after 2011-09-01 up to 2011-11-03 always generated an exponent value…

All CVEs affecting Ruby-lang Ruby →

Other CWE-22 (Path Traversal) vulnerabilities

• CVE-2026-76606 — Critical (CVSS 10.0): Joomla Extension - fabrikar.com - Path Traversal via image element in Fabrik < 4.7.3 - ???.
• CVE-2026-18051 — Critical (CVSS 10.0): The W3 Total Cache WordPress plugin before 2.10.5 does not properly validate the request path it uses to build cache…
• CVE-2026-74764 — Critical (CVSS 10.0): Pandora contains a path traversal vulnerability in its TAR archive extraction functionality. When processing a…
• CVE-2026-16940 — Critical (CVSS 10.0): The Custom Fields WordPress plugin before 1.5.1 does not validate a user-supplied file path before deletion, allowing…
• CVE-2026-67429 — Critical (CVSS 10.0): Flyto2 Core is an execution kernel for automation and AI-agent workflows. Prior to 2.26.6, image.download and related…
• CVE-2026-59555 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Deletion in Participants Database <= 2.7.8.3 versions.

Browse all CWE-22 (Path Traversal) vulnerabilities →