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Vulnerability details: VCID-jadb-cp7x-6qes
Vulnerability ID VCID-jadb-cp7x-6qes
Aliases CVE-2020-12387
Summary A race condition when running shutdown code for Web Worker led to a use-after-free vulnerability. This resulted in a potentially exploitable crash.
Status Published
Exploitability 0.5
Weighted Severity 9.0
Risk 4.5
Affected and Fixed Packages Package Details
Weaknesses (2)
CWE-416 Use After Free
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
System Score Found at
cvssv3 8.8 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-12387.json
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
epss 0.00998 https://api.first.org/data/v1/epss?cve=CVE-2020-12387
cvssv3.1 8.8 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv2 6.8 https://nvd.nist.gov/vuln/detail/CVE-2020-12387
cvssv3.1 8.1 https://nvd.nist.gov/vuln/detail/CVE-2020-12387
archlinux Critical https://security.archlinux.org/AVG-1148
archlinux Critical https://security.archlinux.org/AVG-1155
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2020-16
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2020-17
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2020-18
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-12387.json
https://api.first.org/data/v1/epss?cve=CVE-2020-12387
https://bugzilla.mozilla.org/show_bug.cgi?id=1545345
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-12387
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-12392
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-12395
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-12397
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-6831
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://security.gentoo.org/glsa/202005-03
https://security.gentoo.org/glsa/202005-04
https://www.mozilla.org/security/advisories/mfsa2020-16/
https://www.mozilla.org/security/advisories/mfsa2020-17/
https://www.mozilla.org/security/advisories/mfsa2020-18/
1831761 https://bugzilla.redhat.com/show_bug.cgi?id=1831761
ASA-202005-3 https://security.archlinux.org/ASA-202005-3
ASA-202005-7 https://security.archlinux.org/ASA-202005-7
AVG-1148 https://security.archlinux.org/AVG-1148
AVG-1155 https://security.archlinux.org/AVG-1155
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
CVE-2020-12387 https://nvd.nist.gov/vuln/detail/CVE-2020-12387
mfsa2020-16 https://www.mozilla.org/en-US/security/advisories/mfsa2020-16
mfsa2020-17 https://www.mozilla.org/en-US/security/advisories/mfsa2020-17
mfsa2020-18 https://www.mozilla.org/en-US/security/advisories/mfsa2020-18
RHSA-2020:2031 https://access.redhat.com/errata/RHSA-2020:2031
RHSA-2020:2032 https://access.redhat.com/errata/RHSA-2020:2032
RHSA-2020:2033 https://access.redhat.com/errata/RHSA-2020:2033
RHSA-2020:2036 https://access.redhat.com/errata/RHSA-2020:2036
RHSA-2020:2037 https://access.redhat.com/errata/RHSA-2020:2037
RHSA-2020:2046 https://access.redhat.com/errata/RHSA-2020:2046
RHSA-2020:2047 https://access.redhat.com/errata/RHSA-2020:2047
RHSA-2020:2048 https://access.redhat.com/errata/RHSA-2020:2048
RHSA-2020:2049 https://access.redhat.com/errata/RHSA-2020:2049
RHSA-2020:2050 https://access.redhat.com/errata/RHSA-2020:2050
USN-4353-1 https://usn.ubuntu.com/4353-1/
USN-4373-1 https://usn.ubuntu.com/4373-1/
No exploits are available.
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2020-12387.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: AV:N/AC:M/Au:N/C:P/I:P/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2020-12387
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2020-12387
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.76038
EPSS Score 0.00998
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:09:39.467070+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2020/mfsa2020-18.yml 37.0.0