CVE-2020-12395

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: HIGH) published 2022-05-24. 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: 2.5%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Mozilla developers and community members reported memory safety bugs present in Firefox 75 and Firefox ESR 68.7. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 68.8, Firefox < 76, and Thunderbird < 68.8.0.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
50
EG Risk 50/100CISA SSVC

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%
Exploitation3% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track* or Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
2.5%
EPSS %ILE
84th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact total (CVSS ≥ 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

May 26, 2020

Last Modified

November 21, 2024

Advisory Details (6)

Auto-updated Oct 4, 2026
Patch available.
generic

Mozilla Firefox: Multiple vulnerabilities (GLSA 202005-04) — Gentoo security

https://security.gentoo.org/glsa/202005-04
generic

Mozilla Thunderbird: Multiple vulnerabilities (GLSA 202005-03) — Gentoo security

https://security.gentoo.org/glsa/202005-03
generic

Client Challenge

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1595886%2C1611482%2C1614704%2C1624098%2C1625749%2C1626382%2C1628076%2C1631508
generic

Security Vulnerabilities fixed in Thunderbird 68.8.0 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2020-18/
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/

Patch Availability(12)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntuxul-ext-lightning (1:68.8.0+build2-0ubuntu0.18.04.2) @ bionic2026-05-27ubuntu
ubuntufirefox-mozsymbols (76.0+build2-0ubuntu0.16.04.1) @ xenial2026-05-27ubuntu
redhatthunderbird-0:68.8.0-1.el6_102020-05-11redhat
redhatthunderbird-0:68.8.0-1.el7_82020-05-11redhat
redhatthunderbird-0:68.8.0-1.el8_02020-05-11redhat
redhatthunderbird-0:68.8.0-1.el8_22020-05-11redhat
redhatthunderbird-0:68.8.0-1.el8_12020-05-11redhat
redhatfirefox-0:68.8.0-1.el6_102020-05-06redhat
redhatfirefox-0:68.8.0-1.el8_02020-05-06redhat
redhatfirefox-0:68.8.0-1.el7_82020-05-06redhat
redhatfirefox-0:68.8.0-1.el8_22020-05-06redhat
redhatfirefox-0:68.8.0-1.el8_12020-05-06redhat

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.

Affected Packages

(14 across 7 ecosystems)
Debian:10(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr60.7.2esr-1 ... 68.8.0esr-1~deb9u1 (46 versions)
  • every version up to 68.8.0esr-1~deb10u1: fixed in 68.8.0esr-1~deb10u1
—
thunderbird1:60.7.2-1 ... 1:68.8.0-1~deb9u1 (46 versions)
  • every version up to 1:68.8.0-1~deb10u1: fixed in 1:68.8.0-1~deb10u1
—
Debian:11(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr—
  • every version up to 68.8.0esr-1: fixed in 68.8.0esr-1
—
thunderbird—
  • every version up to 1:68.8.0-1: fixed in 1:68.8.0-1
—
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr—
  • every version up to 68.8.0esr-1: fixed in 68.8.0esr-1
—
thunderbird—
  • every version up to 1:68.8.0-1: fixed in 1:68.8.0-1
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr—
  • every version up to 68.8.0esr-1: fixed in 68.8.0esr-1
—
thunderbird—
  • every version up to 1:68.8.0-1: fixed in 1:68.8.0-1
—
Debian:14(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr—
  • every version up to 68.8.0esr-1: fixed in 68.8.0esr-1
—
thunderbird—
  • every version up to 1:68.8.0-1: fixed in 1:68.8.0-1
—
Debian:8(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr45.0.1esr-1 ... 68.7.0esr-1~deb9u1 (190 versions)
  • every version up to 68.8.0esr-1~deb8u1: fixed in 68.8.0esr-1~deb8u1
—
thunderbird1.5-4 ... 1:68.7.0-1~deb9u1 (126 versions)
  • every version up to 1:68.8.0-1~deb8u1: fixed in 1:68.8.0-1~deb8u1
—
Debian:9(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr45.9.0esr-1 ... 68.8.0esr-1~deb8u1 (153 versions)
  • every version up to 68.8.0esr-1~deb9u1: fixed in 68.8.0esr-1~deb9u1
—
thunderbird1.5-4 ... 1:68.8.0-1~deb8u1 (127 versions)
  • every version up to 1:68.8.0-1~deb9u1: fixed in 1:68.8.0-1~deb9u1
—

Weakness Classification(2)

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

All Vendor Advisories

(12)

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 5× in last 7d / 25× 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 162 total refreshes for this CVE.

  1. 2026-10-05 17:39 UTCEPSS rescore
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  7. 2026-09-27 02:45 UTCOSV refresh
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  27. 2026-08-05 13:11 UTCOSV refresh
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  49. 2026-07-19 12:00 UTCOSV refresh
  50. 2026-07-19 02:26 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2020-12395?
CVE-2020-12395 is a critical vulnerability published on May 26, 2020. Mozilla developers and community members reported memory safety bugs present in Firefox 75 and Firefox ESR 68.7. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects…
When was CVE-2020-12395 disclosed?
CVE-2020-12395 was first published 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-2020-12395 actively exploited?
CVE-2020-12395 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2.5% probability of exploitation in the next 30 days (84th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2020-12395?
CVE-2020-12395 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2020-12395?
A fix for CVE-2020-12395 is available: update to the fixed version the vendor names in its advisory.

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