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CVE Record

CVE-2017-7803: When a page's content security policy (CSP) header contains a "sandbox" directive, other directives are ign...

When a page's content security policy (CSP) header contains a "sandbox" directive, other directives are ignored. This results in the incorrect enforcement of CSP. 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 analysismoderate

Security readout for executives and security teams

Plain-English summary

Older Mozilla clients could mishandle websites that used CSP sandboxing. When the sandbox directive appeared, other security rules in the same policy could be ignored, weakening protections a site expected the browser or mail client to enforce.

Executive priority

Prioritize cleanup if legacy browser or mail clients are still present. This is not shown as actively exploited, but affected clients weaken a core web security control and should not remain in production.

Technical view

CVE-2017-7803 is an incorrect CSP enforcement issue affecting Thunderbird before 52.3, Firefox ESR before 52.3, and Firefox before 55. A CSP header containing sandbox caused other directives to be ignored, potentially bypassing intended browser-side content restrictions.

Likely exposure

Exposure is mainly legacy Mozilla Firefox, Firefox ESR, or Thunderbird installations below the fixed versions. Modern managed endpoints are unlikely to be exposed unless old ESR, distro packages, or embedded browser workflows remain in use.

Exploitation context

The provided sources do not show KEV listing or active exploitation. The risk depends on users rendering attacker-controlled web or email content where affected clients fail to enforce intended CSP restrictions.

Researcher notes

Evidence is limited to vendor and CVE descriptions. No CVSS vector, CWE, exploit status, or detailed root-cause notes are included in the provided bundle. Avoid assuming impact beyond incorrect CSP directive enforcement.

Mitigation direction

  • Upgrade Firefox to version 55 or later.
  • Upgrade Firefox ESR and Thunderbird to version 52.3 or later.
  • Apply fixed vendor packages from Debian, Red Hat, Gentoo, or equivalent distributions.
  • Remove unsupported legacy Mozilla clients from managed endpoints.
  • Check Mozilla and OS vendor advisories for environment-specific guidance.

Validation and detection

  • Inventory Firefox, Firefox ESR, and Thunderbird versions across endpoints.
  • Confirm no Firefox versions below 55 remain installed.
  • Confirm no Firefox ESR or Thunderbird versions below 52.3 remain installed.
  • Check Linux package versions against vendor security advisories.
  • Review applications relying on CSP sandbox plus additional directives.
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

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CVE-2017-7803 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.