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CVE Record

CVE-2017-7807: A mechanism that uses AppCache to hijack a URL in a domain using fallback by serving the files from a sub-p...

A mechanism that uses AppCache to hijack a URL in a domain using fallback by serving the files from a sub-path on the domain. This has been addressed by requiring fallback files be inside the manifest directory. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This issue let Mozilla clients mishandle AppCache fallback behavior so content from a sub-path could take over a URL elsewhere on the same domain. The source bundle names fixes in Firefox, Firefox ESR, and Thunderbird. Business risk is mainly from unmanaged legacy browsers or mail clients still below the fixed versions.

Executive priority

Treat this as a legacy exposure cleanup item unless old Mozilla clients remain in production. It is not KEV-listed in the supplied data, but affected browser or mail clients should be updated or retired.

Technical view

CVE-2017-7807 concerns AppCache fallback URL handling. Mozilla addressed it by requiring fallback files to be inside the manifest directory. The affected products listed are Thunderbird before 52.3, Firefox ESR before 52.3, and Firefox before 55. No CVSS, CWE, or exploitation evidence is provided in the bundle.

Likely exposure

Exposure is likely limited to endpoints running old Mozilla Firefox, Firefox ESR, or Thunderbird versions below the fixed releases, including distribution-packaged builds referenced by Debian, Red Hat, and Gentoo advisories.

Exploitation context

The bundle does not show KEV listing or active exploitation. It describes a URL hijack mechanism using AppCache fallback, but does not provide enough evidence to assess real-world exploit prevalence or required user interaction.

Researcher notes

The supplied data lacks CVSS, CWE, exploit references, and detailed attack preconditions. Analysis should stay tied to Mozilla Bugzilla 1376459 and Mozilla advisories MFSA2017-18, MFSA2017-19, and MFSA2017-20 for technical confirmation.

Mitigation direction

  • Upgrade Firefox to version 55 or later.
  • Upgrade Firefox ESR and Thunderbird to version 52.3 or later.
  • Apply relevant Debian, Red Hat, or Gentoo security updates where used.
  • Remove unsupported legacy Mozilla clients from managed endpoints.
  • Check Mozilla and OS vendor advisories for package-specific guidance.

Validation and detection

  • Inventory installed Firefox, Firefox ESR, and Thunderbird versions.
  • Flag Firefox below 55 as affected.
  • Flag Firefox ESR or Thunderbird below 52.3 as affected.
  • Confirm Linux distribution packages include the referenced 2017 security updates.
  • Review endpoint management data for unmanaged legacy browser installs.
Prepared
Confidence
medium
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

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CVE-2017-7807 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
10Source 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 ESRunspecifiedListed
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.