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CVE Record

CVE-2017-7814: File downloads encoded with "blob:" and "data:" URL elements bypassed normal file download checks though th...

File downloads encoded with "blob:" and "data:" URL elements bypassed normal file download checks though the Phishing and Malware Protection feature and its block lists of suspicious sites and files. This would allow malicious sites to lure users into downloading executables that would otherwise be detected as suspicious. This vulnerability affects Firefox < 56, Firefox ESR < 52.4, and Thunderbird < 52.4.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2017-7814 let malicious websites disguise downloads using blob: or data: URLs so Mozilla’s Phishing and Malware Protection checks could be bypassed. The practical risk was malware delivery: users could be persuaded to download executables that would otherwise be flagged as suspicious.

Executive priority

Treat this as a legacy hygiene and malware-prevention issue. It is not currently evidenced as actively exploited in the provided sources, but vulnerable clients weaken a basic safety control against malicious downloads.

Technical view

Mozilla states that downloads encoded with blob: and data: URL elements bypassed normal download checks and related block lists. Affected products were Firefox before 56, Firefox ESR before 52.4, and Thunderbird before 52.4. The sources do not provide CVSS, CWE, or detailed exploit mechanics.

Likely exposure

Exposure is mainly legacy desktop environments still running Firefox below 56, Firefox ESR below 52.4, or Thunderbird below 52.4, including Linux distributions shipping vulnerable packaged builds before their 2017 security updates.

Exploitation context

The source bundle does not show CISA KEV listing or confirmed active exploitation. The vulnerability supports social-engineering malware delivery by weakening browser or mail-client download reputation checks, but it does not by itself establish automatic code execution.

Researcher notes

Focus validation on product version and distribution patch lineage. The public description is concise and does not include CVSS, CWE, exploit status, or low-level root-cause detail beyond blob: and data: download check bypass behavior.

Mitigation direction

  • Upgrade Firefox to version 56 or later.
  • Upgrade Firefox ESR to version 52.4 or later.
  • Upgrade Thunderbird to version 52.4 or later.
  • Apply relevant Debian, Red Hat, Gentoo, or vendor package updates.
  • Retire unsupported Mozilla browser or mail-client builds.

Validation and detection

  • Inventory endpoint Firefox, Firefox ESR, and Thunderbird versions.
  • Confirm packaged builds include the 2017 vendor security updates.
  • Check software management data for unsupported Mozilla versions.
  • Review security telemetry for suspicious executable downloads from legacy clients.
  • Confirm download protection remains enabled after upgrade.
Prepared
Confidence
high
Sources
11

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-2017-7814 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
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.