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CVE Record

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...

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Ruby flaw can let an application read or interact with a different directory than intended when unsafe path input reaches certain Dir methods. Business risk depends on whether vulnerable Ruby versions process user-controlled directory paths. The public sources name fixed Ruby releases, but provide no CVSS score or confirmed active exploitation.

Executive priority

Treat this as a targeted maintenance priority for systems still running old Ruby. It is not supported here as an emergency exploitation event, but directory traversal can become serious in applications that expose filesystem features.

Technical view

Ruby Dir.open, Dir.new, Dir.entries, and Dir.empty? failed to check NULL characters in affected releases. Ruby describes this as a poisoned NUL byte issue that may cause unintended directory traversal. Fixed versions include 2.2.10, 2.3.7, 2.4.4, and 2.5.1; 2.6.0-preview1 is affected.

Likely exposure

Exposure is most likely in Ruby applications on pre-fixed interpreters that pass externally influenced paths into affected Dir methods. Packaged Ruby from Linux distributions may also be affected until the relevant vendor security update is applied.

Exploitation context

The provided bundle does not show CISA KEV listing or confirmed active exploitation. Public sources establish the vulnerability and vendor updates, but do not provide exploit prevalence or a complete severity score.

Researcher notes

Focus analysis on NULL-byte handling and data flow into Ruby directory APIs. Evidence is strong for affected versions and fixed releases, but incomplete for CVSS, CWE, exploit activity, and application-level impact.

Mitigation direction

  • Upgrade Ruby to the fixed release for the deployed branch.
  • Apply vendor security updates from the operating system distribution.
  • Reject or normalize unsafe path input before directory operations.
  • Review vendor guidance for unsupported Ruby branches and packaged runtimes.
  • Constrain application filesystem permissions to reduce traversal impact.

Validation and detection

  • Inventory Ruby versions across production, CI, and build images.
  • Confirm patched package versions from Ruby or distribution advisories.
  • Search code for affected Dir methods receiving external path input.
  • Review file upload, archive, and browsing features for path handling.
  • Record compensating controls where immediate upgrade is not possible.
Prepared
Confidence
medium
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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description · low confidence lookup

File access behavior lookup

The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2018-8780 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
18Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.