CVE-2017-7821

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-13. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 2%CVSS: 9.8Exploit: None knownExposed: 0

A fix is available — apply it.

A vulnerability where WebExtensions can download and attempt to open a file of some non-executable file types. This can be triggered without specific user interaction for the file download and open actions. This could be used to trigger known vulnerabilities in the programs that handle those document types. This vulnerability affects Firefox < 56.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation2% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
2%
EPSS %ILE
79%
KEV
Not listed

Published

June 11, 2018

Last Modified

November 21, 2024

Advisory Details (4)

Auto-updated Sep 5, 2026
No patch confirmed yet.
generic

Security vulnerabilities fixed in Firefox 56 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2017-21/
generic

1346515 - (CVE-2017-7821) browser.downloads addon feature may be used for RCE

https://bugzilla.mozilla.org/show_bug.cgi?id=1346515
generic

CVE-2017-7817 - PSIRT.COM

http://www.securityfocus.com/bid/101057
generic
http://www.securitytracker.com/id/1039465

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntufirefox-testsuite (56.0+build6-0ubuntu0.14.04.1) @ trusty2026-05-28ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 6× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 130 total refreshes for this CVE.

  1. 2026-09-07 15:56 UTCEPSS rescore
  2. 2026-09-05 15:24 UTCEPSS rescore
  3. 2026-09-04 13:56 UTCEPSS rescore
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  1. 2026-08-02 02:23 UTCEPSS rescore
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  6. 2026-07-28 15:32 UTCEPSS rescore
  7. 2026-07-26 14:51 UTCEPSS rescore
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  9. 2026-07-23 14:15 UTCEPSS rescore
  10. 2026-07-23 01:30 UTCEG score recompute
  11. 2026-07-22 22:10 UTCEG score recompute
  12. 2026-07-22 14:04 UTCEPSS rescore
  13. 2026-07-21 15:21 UTCEPSS rescore
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  21. 2026-07-16 16:59 UTCEPSS rescore
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  23. 2026-07-15 16:55 UTCEPSS rescore
  24. 2026-07-15 16:54 UTCEPSS rescore
  25. 2026-07-15 01:56 UTCEPSS rescore
  26. 2026-07-15 01:56 UTCEPSS rescore
  27. 2026-07-13 22:26 UTCEPSS rescore
  28. 2026-07-13 22:26 UTCEPSS rescore
  29. 2026-07-12 05:43 UTCEPSS rescore
  30. 2026-07-09 19:06 UTCEPSS rescore
  31. 2026-07-08 15:11 UTCEPSS rescore
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  42. 2026-06-30 23:19 UTCEPSS rescore
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  44. 2026-06-29 14:03 UTCEPSS rescore
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  46. 2026-06-28 04:53 UTCEPSS rescore
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  48. 2026-06-27 03:06 UTCEPSS rescore
  49. 2026-06-25 13:47 UTCEPSS rescore
  50. 2026-06-24 14:02 UTCEPSS rescore
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  58. 2026-06-21 01:57 UTCEPSS rescore
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  60. 2026-06-19 19:23 UTCEPSS rescore
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  73. 2026-06-10 22:15 UTCEPSS rescore
  74. 2026-06-10 13:19 UTCEPSS rescore
  75. 2026-06-08 14:14 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2017-7821?
CVE-2017-7821 is a critical vulnerability published on June 11, 2018. A vulnerability where WebExtensions can download and attempt to open a file of some non-executable file types. This can be triggered without specific user interaction for the file download and open actions. This could be used to trigger known vulnerabilities in the programs that handle those…
When was CVE-2017-7821 disclosed?
CVE-2017-7821 was first published in the National Vulnerability Database on June 11, 2018, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2017-7821 actively exploited?
CVE-2017-7821 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2% probability of exploitation in the next 30 days, which ranks it in the top 21.1% of all scored CVEs.
What is the CVSS score of CVE-2017-7821?
CVE-2017-7821 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2017-7821?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2017-7821, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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