CVE-2020-12388

CRITICALNVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

Score 10.0 from GitHub Security Advisory (severity: HIGH) published 2022-05-24. NVD baseline CVSS 10.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
10.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 3%CVSS: 10.0Exploit: None knownExposed: 0

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

The Firefox content processes did not sufficiently lockdown access control which could result in a sandbox escape. *Note: this issue only affects Firefox on Windows operating systems.*. This vulnerability affects Firefox ESR < 68.8 and Firefox < 76.

CVSS v3
10.0
EG Score
10.0(medium)
EG Risk
51(Track)
EG Risk 51/100SSVC: 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
Severity100% × 45%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
3%
EPSS %ILE
85%
KEV
Not listed

Published

May 26, 2020

Last Modified

November 21, 2024

Advisory Details (4)

Auto-updated Aug 15, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic

Security Vulnerabilities fixed in Firefox ESR 68.8 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2020-17/
generic

Security Vulnerabilities fixed in Firefox 76 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2020-16/
generic🟡 PoC Available

1618911 - (CVE-2020-12388) Firefox: Default Content Process DACL Sandbox Escape

https://bugzilla.mozilla.org/show_bug.cgi?id=1618911
generic

Locked Out | Packet Storm

http://packetstormsecurity.com/files/157860/Firefox-Default-Content-Process-DACL-Sandbox-Escape.html

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 29× 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 122 total refreshes for this CVE.

  1. 2026-08-20 22:51 UTCEPSS rescore
  2. 2026-08-19 17:00 UTCEPSS rescore
  3. 2026-08-18 13:44 UTCEPSS rescore
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  1. 2026-07-23 14:15 UTCEPSS rescore
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  3. 2026-07-23 01:48 UTCEG score recompute
  4. 2026-07-22 22:33 UTCEG score recompute
  5. 2026-07-22 14:05 UTCEPSS rescore
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  8. 2026-07-20 17:04 UTCEPSS rescore
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  22. 2026-07-09 19:06 UTCEPSS rescore
  23. 2026-07-08 15:11 UTCEPSS rescore
  24. 2026-07-07 13:43 UTCEPSS rescore
  25. 2026-07-06 16:25 UTCEPSS rescore
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  27. 2026-07-06 02:20 UTCEPSS rescore
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  44. 2026-06-22 14:23 UTCEPSS rescore
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  46. 2026-06-21 14:54 UTCEPSS rescore
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  48. 2026-06-21 01:57 UTCEPSS rescore
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  50. 2026-06-19 19:23 UTCEPSS rescore
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  52. 2026-06-18 17:50 UTCEPSS rescore
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  65. 2026-06-10 22:16 UTCEPSS rescore
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  70. 2026-06-07 15:23 UTCEPSS rescore
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  72. 2026-06-06 13:45 UTCEPSS rescore
  73. 2026-06-06 13:45 UTCEPSS rescore
  74. 2026-06-06 13:45 UTCEPSS rescore
  75. 2026-06-05 22:45 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2020-12388?
CVE-2020-12388 is a critical vulnerability published on May 26, 2020. The Firefox content processes did not sufficiently lockdown access control which could result in a sandbox escape. Note: this issue only affects Firefox on Windows operating systems.. This vulnerability affects Firefox ESR < 68.8 and Firefox < 76.
When was CVE-2020-12388 disclosed?
CVE-2020-12388 was first published in the National Vulnerability Database on May 26, 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-2020-12388 actively exploited?
CVE-2020-12388 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3% probability of exploitation in the next 30 days, which ranks it in the top 15.2% of all scored CVEs.
What is the CVSS score of CVE-2020-12388?
CVE-2020-12388 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2020-12388?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-12388, 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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