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CVE Record

CVE-2018-4377: A cross-site scripting issue existed in Safari.

A cross-site scripting issue existed in Safari. This issue was addressed with improved URL validation. This issue affected versions prior to iOS 12.1, watchOS 5.1, Safari 12.0.1, iTunes 12.9.1, iCloud for Windows 7.8.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2018-4377 is an Apple cross-site scripting issue tied to Safari URL validation. Apple says it was fixed by improved URL validation in iOS 12.1, watchOS 5.1, Safari 12.0.1, iTunes 12.9.1, and iCloud for Windows 7.8. The public bundle does not provide CVSS, CWE, or active exploitation evidence.

Executive priority

Treat this as a legacy patch hygiene issue unless your environment still runs the affected versions. There is no source-backed active exploitation signal in the bundle, but outdated browsers and client software can create avoidable user-driven risk.

Technical view

The vulnerability is described as cross-site scripting in Safari caused by insufficient URL validation. Apple fixed it in multiple platform and application releases. The source bundle does not describe the vulnerable code path, attack preconditions, affected URL patterns, or proof-of-concept details.

Likely exposure

Exposure is most likely on legacy Apple endpoints or Windows systems running versions older than iOS 12.1, watchOS 5.1, Safari 12.0.1, iTunes 12.9.1, or iCloud for Windows 7.8.

Exploitation context

The source bundle marks KEV as false and provides no cited evidence of active exploitation. Because this is an XSS issue in Safari, exposure likely depends on users reaching content that triggers the validation flaw, but the sources do not detail the attack path.

Researcher notes

Public details are sparse. Apple attributes remediation to improved URL validation, but the bundle lacks CVSS, CWE, exploitability metrics, proof-of-concept references, and precise trigger conditions. Avoid assuming broader product impact beyond the named fixed versions.

Mitigation direction

  • Update iOS devices to iOS 12.1 or later.
  • Update watchOS devices to watchOS 5.1 or later.
  • Update Safari to 12.0.1 or later.
  • Update iTunes for Windows to 12.9.1 or later.
  • Update iCloud for Windows to 7.8 or later.
  • Consult Apple advisories for environment-specific guidance.

Validation and detection

  • Inventory endpoints for affected Apple and Windows software versions.
  • Confirm installed versions meet or exceed Apple's fixed releases.
  • Flag unsupported legacy devices that cannot receive fixed versions.
  • Review vulnerability scanners for CVE-2018-4377 detections.
  • Check patch management records for Apple security update completion.
Prepared
Confidence
medium
Sources
7

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2018-4377 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
6Source 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/aiOS, watchOS, Safari, iTunes for Windows, iCloud for WindowsVersions prior to: iOS 12.1, watchOS 5.1, Safari 12.0.1, iTunes 12.9.1, iCloud for Windows 7.8Listed
Weakness

CWE details

No CWE listed

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