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CVE Record

CVE-2019-11730: A vulnerability exists where if a user opens a locally saved HTML file, this file can use file: URIs to acc...

A vulnerability exists where if a user opens a locally saved HTML file, this file can use file: URIs to access other files in the same directory or sub-directories if the names are known or guessed. The Fetch API can then be used to read the contents of any files stored in these directories and they may uploaded to a server. It was demonstrated that in combination with a popular Android messaging app, if a malicious HTML attachment is sent to a user and they opened that attachment in Firefox, due to that app's predictable pattern for locally-saved file names, it is possible to read attachments the victim received from other correspondents. This vulnerability affects Firefox ESR < 60.8, Firefox < 68, and Thunderbird < 60.8.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

An old Mozilla flaw allowed a malicious local HTML file to read nearby local files when their names were known or guessable, then send their contents elsewhere. The main business risk is data leakage from users opening untrusted HTML attachments in affected Firefox or Thunderbird versions.

Executive priority

Treat as moderate priority unless affected legacy browsers remain in active use. The issue enables sensitive local file disclosure, but available sources require user interaction and do not show active exploitation.

Technical view

CVE-2019-11730 affects Firefox ESR before 60.8, Firefox before 68, and Thunderbird before 60.8. A locally saved HTML file could use file: URIs and Fetch API access to read same-directory or subdirectory files with predictable names. Mozilla reported a demonstrated Android messaging-app scenario involving predictable saved attachment names.

Likely exposure

Exposure is most likely on legacy endpoints or Linux distributions still running affected Mozilla packages, especially workflows where users open locally saved HTML attachments in Firefox or Thunderbird handles untrusted local content.

Exploitation context

The bundle describes a demonstrated attack scenario with a popular Android messaging app. It does not cite CISA KEV listing, active exploitation, public exploit code, or broad in-the-wild abuse telemetry.

Researcher notes

Key constraints are local-file execution, same-directory or subdirectory access, and known or guessable filenames. The source bundle lacks CVSS, CWE mapping, and exploit telemetry, so validation should focus on version exposure and risky attachment workflows.

Mitigation direction

  • Upgrade Firefox to 68 or later.
  • Upgrade Firefox ESR to 60.8 or later.
  • Upgrade Thunderbird to 60.8 or later.
  • Apply relevant Debian, openSUSE, or Gentoo security updates.
  • Avoid opening untrusted locally saved HTML attachments.
  • Check Mozilla and distribution guidance for legacy builds.

Validation and detection

  • Inventory installed Firefox, Firefox ESR, and Thunderbird versions.
  • Confirm package updates include the 2019 Mozilla security fixes.
  • Review endpoints that open HTML attachments from messaging or mail apps.
  • Check whether legacy images contain affected Mozilla packages.
  • Validate user guidance for untrusted local HTML files.
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

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CVE-2019-11730 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
9Source 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
MozillaFirefox ESRunspecifiedListed
MozillaFirefoxunspecifiedListed
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.