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CVE Record

CVE-2017-7763: Default fonts on OS X display some Tibetan characters as whitespace.

Default fonts on OS X display some Tibetan characters as whitespace. When used in the addressbar as part of an IDN this can be used for domain name spoofing attacks. Note: This attack only affects OS X operating systems. Other operating systems are unaffected. This vulnerability affects Firefox < 54, Firefox ESR < 52.2, and Thunderbird < 52.2.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

On macOS, vulnerable Mozilla products could show some Tibetan characters as blank space in the address bar. A malicious internationalized domain name could therefore look like a trusted domain, increasing phishing risk. The source states this affects only OS X, not other operating systems.

Executive priority

Prioritize as a legacy phishing-enablement risk, not an emergency infrastructure compromise. If affected Mozilla products remain on macOS, remediate promptly because spoofed domains can support credential theft and fraud.

Technical view

CVE-2017-7763 is an IDN display spoofing issue caused by default OS X fonts rendering selected Tibetan characters as whitespace. It affects Firefox before 54, Firefox ESR before 52.2, and Thunderbird before 52.2. The source does not describe code execution or privilege escalation.

Likely exposure

Exposure is mainly legacy macOS endpoints running affected Firefox, Firefox ESR, or Thunderbird versions. Non-OS X systems are stated as unaffected. Modern deployments are unlikely exposed if browsers and mail clients have been kept current.

Exploitation context

The cited bundle supports phishing-style domain spoofing risk through address-bar deception. It does not state active exploitation, and the CVE is not marked in KEV. Treat exploitation evidence as incomplete unless Mozilla or other trusted advisories say otherwise.

Researcher notes

Key constraints are OS X-only exposure and affected Mozilla versions below the stated fixed ranges. The bundle provides no CVSS, CWE, confirmed exploitation, or detailed patch mechanics. Avoid expanding impact beyond address-bar/domain spoofing without additional vendor evidence.

Mitigation direction

  • Upgrade Firefox to version 54 or later where applicable.
  • Upgrade Firefox ESR to version 52.2 or later where applicable.
  • Upgrade Thunderbird to version 52.2 or later where applicable.
  • Review Mozilla advisories for product-specific remediation guidance.
  • Reduce reliance on vulnerable legacy macOS browser and mail clients.

Validation and detection

  • Inventory macOS endpoints for Firefox, Firefox ESR, and Thunderbird versions.
  • Confirm no Firefox versions below 54 remain in use.
  • Confirm no Firefox ESR or Thunderbird versions below 52.2 remain in use.
  • Check whether IDN handling policies are centrally managed.
  • Review phishing controls for lookalike-domain detection coverage.
Prepared
Confidence
high
Sources
6

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.

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CVE-2017-7763 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
5Source 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
MozillaFirefoxunspecifiedListed
MozillaFirefox ESRunspecifiedListed
MozillaThunderbirdunspecifiedListed
Weakness

CWE details

No CWE listed

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