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CVE Record

CVE-2017-5447: An out-of-bounds read during the processing of glyph widths during text layout.

An out-of-bounds read during the processing of glyph widths during text layout. This results in a potentially exploitable crash and could allow an attacker to read otherwise inaccessible memory. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 45.9, Firefox ESR < 52.1, and Firefox < 53.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is an older Mozilla text-rendering memory-safety flaw. A malicious page or email content using crafted text layout could crash the app and may expose memory. It affects Firefox before 53, Firefox ESR before 45.9/52.1, and Thunderbird before 52.1.

Executive priority

Prioritize as legacy exposure cleanup, not an emergency unless affected versions remain in production. The main business risk is old client software processing untrusted web or email content with a memory disclosure and crash condition.

Technical view

CVE-2017-5447 is an out-of-bounds read while processing glyph widths during text layout. Mozilla described the result as a potentially exploitable crash with possible access to otherwise inaccessible memory. The bundle provides no CVSS, CWE, or detailed exploit mechanics.

Likely exposure

Exposure is likely limited to hosts still running the specified unsupported Mozilla versions. Internet browsing and HTML email rendering are the relevant surfaces if those products remain deployed, especially on legacy desktops or old Linux images.

Exploitation context

The bundle includes an Exploit-DB reference, so public exploit material existed. It does not show CISA KEV listing or confirmed active exploitation. Treat exploitation as plausible against obsolete clients, but not evidenced as currently active from these sources.

Researcher notes

The source bundle identifies the vulnerable component as glyph width processing during text layout. It names affected version thresholds but omits root-cause detail, CVSS, CWE, and concrete remediation beyond upgrading through vendor advisories.

Mitigation direction

  • Upgrade Firefox to 53 or later if still present.
  • Upgrade Firefox ESR to 45.9, 52.1, or later.
  • Upgrade Thunderbird to 52.1 or later if still present.
  • Check Mozilla, Red Hat, and Debian guidance for distribution-specific packages.
  • Remove unsupported Mozilla clients from managed endpoints.

Validation and detection

  • Inventory Firefox, Firefox ESR, and Thunderbird versions across endpoints.
  • Flag Firefox below 53 as affected.
  • Flag Firefox ESR below 45.9 or 52.1 as affected.
  • Flag Thunderbird below 52.1 as affected.
  • Confirm patched packages through OS package management or EDR inventory.
Prepared
Confidence
high
Sources
10

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-2017-5447 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
11Source 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
MozillaThunderbirdunspecifiedListed
MozillaFirefox ESRunspecified, unspecifiedListed
MozillaFirefoxunspecifiedListed
Weakness

CWE details

No CWE listed

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