CVE-2020-15663

HIGHNVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2022-05-24. NVD baseline CVSS 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
8.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 3%CVSS: 8.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

If Firefox is installed to a user-writable directory, the Mozilla Maintenance Service would execute updater.exe from the install location with system privileges. Although the Mozilla Maintenance Service does ensure that updater.exe is signed by Mozilla, the version could have been rolled back to a previous version which would have allowed exploitation of an older bug and arbitrary code execution with System Privileges. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Firefox < 80, Thunderbird < 78.2, Thunderbird < 68.12, Firefox ESR < 68.12, and Firefox ESR < 78.2.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
45(Track)
EG Risk 45/100SSVC: 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
Severity88% × 45%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
84.5%
KEV
Not listed

Published

October 1, 2020

Last Modified

November 21, 2024

References (12)

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 44× 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.

  1. 2026-07-23 01:50 UTCEG score recompute
  2. 2026-07-22 22:35 UTCEG score recompute
  3. 2026-07-22 14:05 UTCEPSS rescore
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  1. 2026-07-06 16:25 UTCEPSS rescore
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  49. 2026-06-01 13:50 UTCEPSS rescore
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  51. 2026-05-31 22:29 UTCEPSS rescore
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  55. 2026-05-29 13:42 UTCEPSS rescore
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  61. 2026-05-24 16:48 UTCEPSS rescore
  62. 2026-05-23 07:06 UTCEG score recompute
  63. 2026-05-23 07:06 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2020-15663?
CVE-2020-15663 is a high vulnerability published on October 1, 2020. If Firefox is installed to a user-writable directory, the Mozilla Maintenance Service would execute updater.exe from the install location with system privileges. Although the Mozilla Maintenance Service does ensure that updater.exe is signed by Mozilla, the version could have been rolled back to a…
When was CVE-2020-15663 disclosed?
CVE-2020-15663 was first published in the National Vulnerability Database on October 1, 2020, 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-2020-15663 actively exploited?
CVE-2020-15663 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 84.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2020-15663?
CVE-2020-15663 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2020-15663?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-15663, 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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